To determine the relative density of soil, a test device is inserted into the soil for investigation. When the effective vertical stress of the soil is $S$ and the resistance force received by the test device as it enters the soil is $R$, the relative density $D ( \% )$ of the soil can be calculated as follows. $$D = - 98 + 66 \log \frac { R } { \sqrt { S } }$$ (Here, the units of $S$ and $R$ are metric ton/$\mathrm{m}^{2}$.) The effective vertical stress of soil A is 1.44 times the effective vertical stress of soil B, and the resistance force received by the test device as it enters soil A is 1.5 times the resistance force received as it enters soil B. When the relative density of soil B is $65 ( \% )$, what is the relative density of soil A (in $\%$)? (Use $\log 2 = 0.3$ for calculation.) [3 points] (1) 81.5 (2) 78.2 (3) 74.9 (4) 71.6 (5) 68.3
To determine the relative density of soil, a test device is inserted into the soil for investigation. When the effective vertical stress of the soil is $S$ and the resistance force received by the test device as it enters the soil is $R$, the relative density $D ( \% )$ of the soil can be calculated as follows.
$$D = - 98 + 66 \log \frac { R } { \sqrt { S } }$$
(Here, the units of $S$ and $R$ are metric ton/$\mathrm{m}^{2}$.)\\
The effective vertical stress of soil A is 1.44 times the effective vertical stress of soil B, and the resistance force received by the test device as it enters soil A is 1.5 times the resistance force received as it enters soil B. When the relative density of soil B is $65 ( \% )$, what is the relative density of soil A (in $\%$)? (Use $\log 2 = 0.3$ for calculation.) [3 points]\\
(1) 81.5\\
(2) 78.2\\
(3) 74.9\\
(4) 71.6\\
(5) 68.3