Question

In a certain store, there is a 0.05 probability that the scanned price in the bar code scanner will not match the advertised price. The cashier scans 850 items.

(a-1)

What is the expected number of mismatches? (Round your answer to the nearest whole number.)

Expected number

(a-2)

What is the standard deviation? (Use your rounded number for the expected number of mismatches for the calculation of standard deviation. Round your final answer to 4 decimal places.)

Standard deviation

(b)	What is the probability of at least 37 mismatches? (Round the z-value to 2 decimal places. Use Appendix C-2 to find probabilities. Round your final answer to 4 decimal places.)

Probability

(c)	What is the probability of more than 49 mismatches? (Round the z-value to 2 decimal places. Use Appendix C-2 to find probabilities. Round your final answer to 4 decimal places.)

Probability

Answer 1

a-1)

expected number of mismatches =np =42.5

a-2)  Standard deviation =(np(1-p))^1/2 =6.3541

b)

probability =

P(X>36.5)

=

P(Z>-0.94)=

1-P(Z<-0.94)=

1-0.1736=

0.8264

c)

probability =

P(X>49.5)

=

P(Z>1.1)=

1-P(Z<1.1)=

1-0.8643=

0.1357