Question

Assume that different groups of couples use a particular method of gender selection and each couple gives birth to one baby. This method is designed to increase the likelihood that each baby will be a? girl, but assume that the method has no? effect, so the probability of a girl is 0.5. Assume that the groups consist of 32 couples. Complete parts? (a) through? (c) below. a. Find the mean and the standard deviation for the numbers of girls in groups of 32 births. The value of the mean is muequals nothing. ?(Type an integer or a decimal. Do not? round.) The value of the standard deviation is sigmaequals nothing. ?(Round to one decimal place as? needed.) b. Use the range rule of thumb to find the values separating results that are significantly low or significantly high. Values of nothing girls or fewer are significantly low. ?(Round to one decimal place as? needed.) Values of nothing girls or greater are significantly high. ?(Round to one decimal place as? needed.) c. Is the result of 26 girls a result that is significantly? high? What does it suggest about the effectiveness of the? method? The result ? is is not significantly? high, because 26 girls is ? less than equal to greater than nothing girls. A result of 26 girls would suggest that the method ? is effective. is not effective. ?(Round to one decimal place as? needed.) Enter your answer in each of the answer boxes.

Answer 1

a) n = number of couples = 32

p = probability of girl = 0.5

Mean = n * p = 32*0.5 = 16

The value of the mean is mu equals 16

Standard deviation = (n * p * (1-p) )^0.5= (32 * 0.5 * (1-0.5))^0.5 = 8^0.5= 2.8

The value of the standard deviation is sigma equals 2.8

b) Using the range rule of thumb,

Minimum value = Mu - 2* sigma = 16 - 2*2.8 = 10.4

Maximum value = Mu - 2* sigma = 16 + 2*2.8 = 21.6

Values of 10.4 girls or fewer are significantly low.

Values of 21.6 girls or greater are significantly high.

c) The result is significantly high, because 26 girls is greater than 21.6 girls.

A result of 26 girls would suggest that the method is not effective.