Probability help

[Underside]

Help with question 9C.
I thought of using normal distribution formula here but the information was not enough for that. Then dumbly thought of using joint conditional probability but with the information given I couldnt use it because the event is independent. I am stuck; can anyone please give me any hints of how to solve it. Thanks.

 

[Romsek]

another Poisson distribution problem.

 

[Underside]

another Poisson distribution problem.

Thanks. I dont know how it slipped my mind. So, basically as shown in my picture below right?

 

[Romsek]

Thanks. I dont know how it slipped my mind. So, basically as shown in my picture below right?

yep