Measures of Location and Spread

All Questions
A survey was conducted with 200 students from a school to find out which type of music they prefer. The results are shown in the pie chart below.
Type of musicPercentage
Pop35\%
Rock25\%
Funk20\%
Sertanejo15\%
Other5\%

How many students prefer Pop or Rock?
(A) 60
(B) 80
(C) 100
(D) 120
(E) 140
The mean of five numbers is 12. If four of the numbers are 8, 10, 14, and 16, what is the fifth number?
(A) 10
(B) 11
(C) 12
(D) 13
(E) 14
A technology company will standardize the internet connection speed it offers to its customers in ten cities. The company's management decides that its new reference speed standard will be the median of the reference speed values of connections in these ten cities. These values, in megabytes per second (MB/s), are presented in the table.
CitiesReference speed (MB/s)
C1390
C2380
C3320
C4390
C5340
C6380
C7390
C8400
C9350
C10360

The reference speed, in megabytes per second, to be adopted by this company is
(A) 360.
(B) 370.
(C) 380.
(D) 390.
(E) 400.
In a clinical study, 55 women were randomly distributed into 5 groups of 11 people. To test a new medication, a group will be chosen in which the majority of women are between 20 and 30 years old. The other groups will take placebo or medications already on the market. The table, partially filled, provides some data related to the ages of women in these groups.
GroupsMinimum ageMaximum ageMeanMedianModeStandard deviation
12510
2259
325
4251
52035

Even with the incomplete table, it was possible to select one of these groups because, with only the data presented in the table, a group was identified that certainly met the selection criterion.
The group chosen was
(A) 1.
(B) 2.
(C) 3.
(D) 4.
(E) 5.
Pace is a term used by a runner to denote his average rhythm in a race. It represents the average time, in seconds, that this runner takes to cover 1 km.
The diagram presents the time, in seconds, that a runner took to cross the marks that define the first four 1 km sections in a 5 km race, and the time spent to cover each 1 km section.
The best pace that this runner achieved in 5 km races was $281\,\mathrm{s/km}$. For him to repeat his best pace in 5 km races in this race, his time in the $5^{\text{th}}$ section should be how many seconds less than what he spent to cover the $4^{\text{th}}$ section?
(A) 1
(B) 2
(C) 8
(D) 9
(E) 15
The productivity of soybeans in a cultivated area is the average quantity of 50-kilogram sacks that are produced per hectare. The table presents the cultivated area and soybean productivity on a certain property, over five harvests, with periods of one year, from 2011 to 2016.
Harvest$\mathbf{11\text{-}12}$$\mathbf{12\text{-}13}$$\mathbf{13\text{-}14}$$\mathbf{14\text{-}15}$$\mathbf{15\text{-}16}$
Cultivated area (hectare)200220250250200
Productivity (sacks of $50\,\mathrm{kg}$ per hectare)4030454550

The line graph that represents the soybean production of this property, in tons, in these five harvests is
(A), (B), (C), (D), or (E) as indicated in the figures.
The probability distribution table of random variable $X$ is shown below. Find the variance of random variable $Y = 10 X + 5$. [3 points]
$X$0123Total
$\mathrm { P } ( X )$$\frac { 2 } { 10 }$$\frac { 3 } { 10 }$$\frac { 3 } { 10 }$$\frac { 2 } { 10 }$1
The following is a stem-and-leaf plot showing the number of push-ups performed by 10 high school students in 3 minutes.
(Unit: times)
Stem\multicolumn{3}{|c|}{Leaf}
159
2378
3266
415

Let $m$ be the mean, $n$ be the median, and $f$ be the mode of the number of push-ups. Which of the following is correct? [3 points]
(1) $m < n < f$
(2) $m < f < n$
(3) $f < m < n$
(4) $n < m < f$
(5) $n < f < m$
The following is a probability distribution table of a certain population.
$X$123Total
$\mathrm { P } ( X )$0.50.30.21

When a sample of size 2 is drawn with replacement from this population, the probability distribution table of the sample mean $\bar { X }$ is as follows.
$\bar { X }$11.522.53
Frequency1$a$$b$21
$\mathrm { P } ( \bar { X } )$0.25$c$$d$0.120.04

Find the value of $100 ( b + c )$. [4 points]
(Probability and Statistics) A certain basketball player practices free throws 40 times every day. The stem-and-leaf plot below shows the number of successful free throws each day for the first 10 days, with the tens digit as the stem and the units digit as the leaf. On the 11th day, the number of successful free throws was $n$, and the average number of successful free throws for the first 11 days was equal to the mode in the stem-and-leaf plot below. What is the value of $n$? [3 points]
Stem\multicolumn{4}{|c|}{Leaf}
09
179
21446
3013

(1) 24
(2) 26
(3) 28
(4) 30
(5) 32
The probability distribution table of the random variable $X$ is as follows.
$X$012Total
$\mathrm { P } ( X = x )$$\frac { 2 } { 7 }$$\frac { 3 } { 7 }$$\frac { 2 } { 7 }$1

What is the value of the variance $\mathrm { V } ( 7 X )$ of the random variable $7 X$? [3 points]
(1) 14
(2) 21
(3) 28
(4) 35
(5) 42
[Probability and Statistics] Which of the following is the correct shape of the graph of the function representing the median according to the value of $x$ in the following data? (where $x \geqq 0$ ) [3 points] $10 , \quad 28 , \quad x , \quad 20 , \quad 8 , \quad 2 , \quad 25 , \quad 7 , \quad 17$
[Probability and Statistics] A training facility has three courses A, B, and C to be experienced in order, with the entrance and exit being the same. There are 30 envelopes at course A, 60 envelopes at course B, and 90 envelopes at course C. Each envelope contains 1, 2, or 3 coupons. The following table shows the number of envelopes by the number of coupons for each course.
\multicolumn{1}{|c|}{Number of Coupons}123Total
A2010030
B30201060
C40302090

After completing each course, a student randomly selects one envelope from that course and receives the coupons inside. A student who started first completed all three courses and received a total of 4 coupons. What is the probability that the student received 2 coupons at course B? [3 points]
(1) $\frac { 6 } { 23 }$
(2) $\frac { 8 } { 23 }$
(3) $\frac { 10 } { 23 }$
(4) $\frac { 12 } { 23 }$
(5) $\frac { 14 } { 23 }$
[Probability and Statistics] A survey of 100 randomly selected people from city A regarding the safest mode of transportation found that 20 people chose express buses. Using this result, a 95\% confidence interval for the proportion of people who chose express buses was found to be $[ a , b ]$. For city B, a 95\% confidence interval is to be constructed for the proportion of people who think express buses are the safest mode of transportation based on a random sample of $n$ people. Find the minimum value of $n$ such that the maximum allowable sampling error of this confidence interval is at most $\frac { b - a } { 2 }$. [4 points]
There are two datasets A and B. The mean and median of dataset A, which consists of 5 distinct numbers, are both 25. Dataset B consists of 7 numbers, where 5 of them match the data in A, and the remaining 2 are $x$ and $y$. Which of the following statements are correct? Choose all that apply from $\langle$Remarks$\rangle$. [4 points]
(1) ㄱ
(2) ㄷ
(3) ㄱ, ㄴ
(4) ㄴ, ㄷ
(5) ㄱ, ㄴ, ㄷ
csat-suneung 2016 Q9 3 marks
Let $\bar { X }$ be the sample mean obtained by randomly extracting a sample of size $n$ from a population with population standard deviation 14. When $\sigma ( \bar { X } ) = 2$, what is the value of $n$? [3 points]
(1) 9
(2) 16
(3) 25
(4) 36
(5) 49
csat-suneung 2020 Q14 4 marks
A bag contains 10 balls labeled with the number 1, 20 balls labeled with the number 2, and 30 balls labeled with the number 3. A ball is drawn at random from the bag, the number on the ball is noted, and the ball is returned. This procedure is repeated 10 times, and let $Y$ be the sum of the 10 numbers observed. The following is the process of finding the mean $\mathrm { E } ( Y )$ and variance $\mathrm { V } ( Y )$ of the random variable $Y$.
Consider the 60 balls in the bag as a population. When a ball is drawn at random from this population, let $X$ be the random variable representing the number on the ball. The probability distribution of $X$, which is the probability distribution of the population, is shown in the following table.
$X$123Total
$\mathrm { P } ( X = x )$$\frac { 1 } { 6 }$$\frac { 1 } { 3 }$$\frac { 1 } { 2 }$1

Therefore, the population mean $m$ and population variance $\sigma ^ { 2 }$ are
$$m = \mathrm { E } ( X ) = \frac { 7 } { 3 } , \quad \sigma ^ { 2 } = \mathrm { V } ( X ) = \text { (가) }$$
When a sample of size 10 is randomly extracted from the population and the sample mean is $\bar { X }$,
$$\mathrm { E } ( \bar { X } ) = \frac { 7 } { 3 } , \quad \mathrm {~V} ( \bar { X } ) = \text { (나) }$$
If the number on the $n$-th ball drawn from the bag is $X _ { n }$, then
$$Y = \sum _ { n = 1 } ^ { 10 } X _ { n } = 10 \bar { X }$$
so
$$\mathrm { E } ( Y ) = \frac { 70 } { 3 } , \quad \mathrm {~V} ( Y ) = \text { (다) }$$
If the numbers that fit (가), (나), and (다) are $p , q , r$ respectively, what is the value of $p + q + r$? [4 points]
(1) $\frac { 31 } { 6 }$
(2) $\frac { 11 } { 2 }$
(3) $\frac { 35 } { 6 }$
(4) $\frac { 37 } { 6 }$
(5) $\frac { 13 } { 2 }$
csat-suneung 2021 Q11 3 marks
A sample of size 16 is randomly extracted from a population following a normal distribution $\mathrm { N } \left( 20,5 ^ { 2 } \right)$, and the sample mean is $\bar { X }$. What is the value of $\mathrm { E} ( \bar { X } ) + \sigma ( \bar { X } )$? [3 points]
(1) $\frac { 91 } { 4 }$
(2) $\frac { 89 } { 4 }$
(3) $\frac { 87 } { 4 }$
(4) $\frac { 85 } { 4 }$
(5) $\frac { 83 } { 4 }$
Point P is at the origin of the coordinate plane. The following trial is performed using one die.
When the die is rolled and the number shown is
2 or less, point P is moved 3 units in the positive direction of the $x$-axis,
3 or more, point P is moved 1 unit in the positive direction of the $y$-axis.
This trial is repeated 15 times, and the distance between the moved point P and the line $3 x + 4 y = 0$ is the random variable $X$. What is the value of $\mathrm { E } ( X )$? [4 points]
(1) 13
(2) 15
(3) 17
(4) 19
(5) 21
There is a bag containing 5 cards with the numbers $1, 3, 5, 7, 9$ written on them, one number per card. A trial is performed by randomly drawing one card from the bag, confirming the number on the card, and putting it back. This trial is repeated 3 times, and let $\bar{X}$ be the average of the three numbers confirmed. When $\mathrm{V}(a\bar{X} + 6) = 24$, what is the value of the positive number $a$? [3 points]
(1) 1
(2) 2
(3) 3
(4) 4
(5) 5
5. A population is divided into three strata $A, B, C$ with individual numbers in the ratio $5:3:2$. If stratified sampling is used to draw a sample of size 100, then the number of individuals to be drawn from $C$ is $\_\_\_\_$.
2. In the ancient Chinese mathematical classic ``The Nine Chapters on the Mathematical Art,'' there is a problem called ``Grain and Chaff Separation'': A grain warehouse receives 1534 shi of rice. Upon inspection, the rice contains chaff. A sample of one handful of rice is taken, and among 254 grains, 28 are chaff. Estimate the amount of chaff in this batch of rice as
A. $ 134$ shi
B. $ 169$ shi
C. $ 338$ shi
D. $ 1365$ shi
2. Given a set of data $4,6,5,8,7,6$, then the mean of this set of data is $\_\_\_\_$ .
gaokao 2015 Q4 5 marks
The stem-and-leaf plot of the average monthly temperatures (in $^\circ$C) in Chongqing in 2013 is shown below.
The median of this data set is
(A) 19
(B) 20
(C) 21.5
(D) 23
gaokao 2015 Q8 5 marks
A certain car fills up its fuel tank every time it refuels. The table below records the situation at two consecutive refueling times. Note: ``Cumulative mileage'' refers to the total distance the car has traveled since leaving the factory. During this period, the average fuel consumption per 100 kilometers for this car is\n\n\n
\n\nRefueling DateRefueling Amount (liters)\begin{tabular}{ c }\nCumulative Mileage at
\nRefueling (kilometers)
\n
\n\hline\nMay 1, 2015 & 12 & 35000 \n\hline\nMay 15, 2015 & 48 & 35600 \n\hline\n\end{tabular}\n