## Poisson distribution!! Need help

Hi,
Need help in solving few poisson distribution questions

q)A dealer receives hard disks made by a certain manufacturer who on an average gives 3 defective pieces. The dealer rejects the sample if there are more than 4 defective pieces in a sample. What is the chances that the dealer will reject the sample?
a.83%
b.18%
c.17%
d.35%

ANS:: am I correct if I solve it :1-POISSON.DIST(4,3,TRUE) IN MSEXCEL
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q)A supplier of company X makes on an average of 5 defective pieces. The company accepts a sample if there are no more than 7 defective pieces. What are the chances that the company will reject the sample?
a.13%
b.86%
c.76%
d.24%

ANS:: am I correct if I solve it: 1-POISSON.DIST(7,5,TRUE) IN MSEXCEL.

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q)At a certain traffic signal red for 30 seconds, yellow for 5 seconds, and green for 25 seconds. Find the probability that out of the next ten cars that arrive randomly at the light, exactly four will be stopped by a red light
a.0.2
b 0.38
c 0.625
d. 0.5

I have no clue how to proceed with this question plz help