If the test contains 250 questions, what is the probability that Jodi will score
ID: 3175490 • Letter: I
Question
If the test contains 250 questions, what is the probability that Jodi will score 71% or lower? How many questions must the test contain in order to reduce the standard deviation of Jodi's proportion of correct answers to half its value for a 100-item test? A sample survey interviews an SRS of 250 college women. Suppose that 65% of all college women have been on a diet within the last 12 months. What is the probability that 74% or more of the women in the sample have been on a diet? Use 4 decimal places.Explanation / Answer
sample szie = 250
Probabilty of women being on diet = 0.65
mean no of women on diet = 250*0.65 = 162.5
variance . = 250*0.65*0.35 = 56.875
standard deviation = 7.54
74% of sample size . = 0.74*250 = 185
z value for 185 using z table is (185-162.5)/7.54 = 2.984 , corresponding p value is 0.998577
Probabity for 74% or less on diet = 0.998577
Probabity for 74% or more women on diet = 1- 0.998577 = 0.0014