Mean and standard deviation

Question

An engineer is redesigning an ejection seat for an airplane. The seat was designed for pilots weighing between 130 lb and 171 lb. the new population of pilots as normally distributed weights with mean of 140 lb and stand deviation of 263 lb. 

If a pilot is randomly selected, find the probability that his weight is between 130 lb and 171 lb. 

Answer 1

Hello Kate,

 

I suspect that there is a misprint in the above question.

 

It seems more likely that the standard deviation is 26.3 lb.

 

Working with 26.3 rather than 263 and the formula (x - μ)/σ, the result is as follows:

 

P(.3530 < z < .8810) =.5290

 

If I work with σ = 263, the result is P( .4840 < z < >5478) = .0638.

 

Regards,

Anita A.