Answer:
About 68% of sixth-grade students will have heights between 55.7 inches and 60.3 inches.
Explanation:
The Empirical rule, also the 68–95–99.7 rule, states that for a population that is approximately normal or symmetrical, nearly all of the data values will lie within three standard deviations of the mean;
68% of data values will fall within one standard deviation from the mean
95% of data values will fall within two standard deviation from the mean
99.7% of data values will fall within three standard deviation from the mean
Now, assuming the heights of the sixth-grade students are approximately normal 68% of these students will have their heights fall within one standard deviation from the mean;
mean ± standard deviation
58 ± 2.3 = (55.7, 60.3)
Therefore, about 68% of sixth-grade students will have heights between 55.7 inches and 60.3 inches.