Answer
$76$ minutes
Work Step by Step
Analyzing the figure on page 241 about the the logarithm of grain diameter versus the logarithm of time for grain growth in brass at several
temperatures (Figure 7.25), it can be approximated that at $700^{o}$ it takes roughly 0 minutes to get to the 0.03 mark and roughly 76 minutes to reach the 0.3 mark. Therefore, the time required can be found by subtracting the two.
$76 minutes $ $- 0minutes$ $= 76minutes$
