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How do i do this Stats / Probability Question?
Can someone show how me how to work out these probability questions?
For a randomly selected child, the probability of IQ less than 106 is P(IQ<106) = 0.7
a. For a group of 12 children, find the probability that at least 5 of them will have IQ's less than 106.
b. For a group of 15 children, find the probability that exactly 10 will have IQ's less than 106.
1 Answer
- 7 years ago
A)
P=.7, n=12
Standard deviation is sqrt(npq) = sqrt(12*.7*.3)=1.59
Your expected amount in a group of 12 is 12*.7=8.4.
Do a z test to see the probability of 5 or more.
Z=(5-8.4)/1.59= -2.13
Look up in a z table, and take 1 - the answer since you want more than 5 and you get .9834
.9834 is your answer.
B)
Look up a binomial probability table, and find the probability when p=.7, n=15, and r=10.
You get .206
