Answer: A) 13
Step-by-step explanation:
Mean - 1 SD: 20.2 - 2.4 = 17.8 --> (18)
Mean + 1 SD: 20.2 + 2.4 = 22.6 --> (23)
Now, find the values on the histogram for 18 through 23:
2 + 3 + 4 + 3 + 1 + 1 = 13
