Question

The accompanying data table describes results from groups of 10 births from 10 different sets of parents. The random variable x represents the number of girls among 10 children. Complete the questions below.

x   P(x)
0   0.002
1   0.016
2   0.037
3   0.114
4   0.201
5   0.238
6   0.198
7   0.113
8   0.045
9   0.014
10   0.022

The maximum usual value is (Round to one decimal place as​ needed.)

The minimum usual value is (Round to one decimal place as​ needed.)

Based on the​ result, is 1 girl in 10 births an unusually low number of​ girls?

A. No, 1 girl is not an unusually low number of​ girls, because 1 girl is less than the minimum usual value.

B.Yes, 1 girl is an unusually low number of​ girls, because 1 girl is outside of the range of usual values.

C.Yes, 1 girl is an unusually low number of​ girls, because 1 girl is less than the maximum usual value.

D. Not enough information is given.

Answer 1

The table for calculation is:

Hence,

Mean = = 5.111

Standard deviation = = 1.764

Therefore,

Maximum usual value = Mean + 2*SD = 5.111 + 2*1.764 = 8.6

Minimum usual value = Mean - 2*SD = 5.111 - 2*1.764 = 1.6

Yes, 1 girl is an unusually low number of​ girls, because 1 girl is outside of the range of usual values. Option B is correct.