Evaluate the Expression Without Using a Calculator $R = \log \left( \frac { \mathrm { a } } { \mathrm { T } } \right) + \mathrm { B }$

Multiple Choice

Evaluate the expression without using a calculator.
-Use the formula $R = \log \left( \frac { \mathrm { a } } { \mathrm { T } } \right) + \mathrm { B }$ to find the intensity $\mathrm { R }$ on the Richter scale, given that amplitude a is 304 micrometers, time T between waves is $3.8$ seconds, and B is 3.1. Round answer to one decimal place.

A) $1.9$
B) $7.4$
C) $7.5$
D) 5