csat-suneung 2013 Q10

csat-suneung · South-Korea · csat__math-science 3 marks Inequalities Inequality Word Problem (Applied/Contextual)
Starting from point A, one travels to point B which is 6 km away, and then returns to point A along the same route. For the first 1 km, one walks at a constant speed, and for the remaining 5 km, one travels at twice the initial walking speed. On the return trip, one travels at a speed 2 km/h faster than the initial walking speed. When the total time for the round trip is at most 2 hours 30 minutes, what is the minimum value of the initial walking speed? (Given that the unit of speed is km/h.) [3 points]
(1) $\frac { 12 } { 5 }$
(2) $\frac { 13 } { 5 }$
(3) $\frac { 14 } { 5 }$
(4) 3
(5) $\frac { 16 } { 5 }$
Starting from point A, one travels to point B which is 6 km away, and then returns to point A along the same route. For the first 1 km, one walks at a constant speed, and for the remaining 5 km, one travels at twice the initial walking speed. On the return trip, one travels at a speed 2 km/h faster than the initial walking speed. When the total time for the round trip is at most 2 hours 30 minutes, what is the minimum value of the initial walking speed?\\
(Given that the unit of speed is km/h.) [3 points]\\
(1) $\frac { 12 } { 5 }$\\
(2) $\frac { 13 } { 5 }$\\
(3) $\frac { 14 } { 5 }$\\
(4) 3\\
(5) $\frac { 16 } { 5 }$