SOLUTION: Records show that 28% of all payments to a mail-order company are submitted after the due date. Suppose 50 payments are submitted this week. Let r be a random varible that repres

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Question 460522: Records show that 28% of all payments to a mail-order company are submitted after the due date. Suppose 50 payments are submitted this week. Let r be a random varible that represents the number of payments that are late. Use the normal approximation to the binomial to estimate:
A. P(r>_ >20)

B. P(20<_ r<_25)

I was unable to place the _ under the < > Signs
_ _
Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
[[[50*.28=14=mu}}}
p=.28
1-.28=.72=q
sigma=sqrt%2850%2A.28%2A.72%29=7.17
.
A)
P(r>=20)
z=(20-14)/7.17
=6/7.17
=0.837
P=.201 area under normal curve above z=0.837
.
B)
z=(25-14)/7.17
=11/7.17
=1.534
p=.063 area under normal curve above z=1.534
.
.201-.063=.138 P(20<=r<=25)
.
Ed