When Natalie runs the 400 meter dash, her finishing times are normally distributed with a mean of 71 seconds and a standard deviation of 2.5 seconds. What percentage of races will her finishing time be between 71 and 77 seconds, to the nearest tenth?

Step 1 ：1. Determine Z-scores: \(Z_1 = \frac{71 - 71}{2.5} = 0\), and \(Z_2 = \frac{77 - 71}{2.5} = 2.4\)

Step 2 ：2. Look up Z-scores in the standard normal table or use a calculator to find the cumulative probabilities: \(P(Z_1) = 0.5\), \(P(Z_2) = 0.9918\)

Step 3 ：3. Calculate the percentage of races between 71 and 77 seconds: \((P(Z_2) - P(Z_1))\times 100 = (0.9918 - 0.5)\times 100 = 49.2\%\)