3. In a survey of soap watchers 65% saythey get good grades. You randomly select

Question

3. In a survey of soap watchers 65% saythey get good grades. You randomly select 50 students and ask them if they get good grades. What is the probability that fewer than 20 respond yes? 45% of all US students say that they never sing in the shower. You randomly select 180 students and ask them if they sing in the shower. What is the probability that at least 120 students will say they never sing in the shower? 4, Nationally, 40% of four-year graduates have no student loans. You randomly select 50 students and determine if they have student loans. What is the probability that exactly 40 of the students have no student loans? 5. ,

Explanation / Answer

Question 3

Pr(Good grades) = 0.65

sample size n = 50

if x is the number of people out of 50, who responded that they have good grades)

Pr(x < 20 ; 50 ; 0.65) = BINOMCDF (x < 20 ; 50 ; 0.65) = 9.01256 x 10-5

Question 4

n = 180

p = 45% = 0.45

Pr(x >= 120 ; 180 ; 0.45) = 1 - BINOMCDF (x < 120 ; 180; 0.45) = 1 - 0.9999 = 0.00001

Question 5

n = 50

p = 0.40

Pr(x = 40) = BIN (x = 40 ; 50 ; 0.40) = 50C40 (0.40)40 (0.60)10 = 7.5 x 10-9

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