Standard normal distribution problem

[EdmureTully]

Homework Statement

(Page 222 number 5) A highway department has enough salt to handle a total of 80 inches of snowfall. Suppose the daily amount of snow has a mean of 1.5 inches and a standard deviation of .3 inches.

Approximate the probability that the salt on hand will suffice for the next 50 days.
What assumption did you make in solving part (a)?
Do you think this assumption is justified? Explain briefly.

Homework Equations

The Attempt at a Solution

I did 1.5x50 and

sqrt(50(0.3)^2)

and got P(Z<2.36)

 

[mfb]

(Page 222 number 5)

In which book?

I did 1.5x50 and

sqrt(50(0.3)^2)

and got P(Z<2.36)

Please don't throw in some numbers without any explanation. What did you assume about the distribution of snow in the next 50 days? What did you calculate, with which formula? Which result did you get?

The numerical value of 2.36 looks good.