Question

A coin is tossed 140 times. The probability of getting tails is p=0.500. Would a result of 55 heads out of the 140 trials be considered usual or unusual? Why?

a. Unusual, because the result is more than the maximum usual value.
b. Unusual, because the result is less than the maximum usual value.

c. Usual, because the result is between the minimum and maximum usual values.
d. Unusual, because the result is less than the minimum usual value.

Answer 1

μ-np-140 x 0.5-70 /np( 1-p)-'140x05x0.5-5916 σ Usual values: Lower Limit-1-2σ 70-(2 x5.916)-58.168 Upper Limit-μ +2σ-704(2x 5.916)-81.832 Note that 55 58.168 Ans:d.Unusual, because the result is less than the minimum usual value.