• Solution
[tex]7^{\frac{x}{10}}=2[/tex]
To solve for x, we take the logarithm of both sides.
[tex]\log 7^{\frac{x}{10}}=\log 2[/tex]Applying the law of logarithm to the equation above;
[tex]\log a^b=b\log a[/tex][tex]\begin{gathered} \log 7^{\frac{x}{10}}=\log 2 \\ \frac{x}{10}\log 7=\log 2 \\ \text{Dividing both sides by log 7;} \\ \frac{x}{10}=\frac{\log 2}{\log 7} \\ \frac{x}{10}=\frac{0.3010}{0.8451} \\ \frac{x}{10}=0.3562 \\ \text{Cross multiplying the equation;} \\ x=0.3562\times10 \\ x=3.562 \end{gathered}[/tex]Therefore, the approximate value of x is 3.562
The correct option is E.
