Q1) A bag of definite brand of popcorn is placed in the microwave oven and time it takes kernel to pop is observed. Assume that time to pop, X, has normal distribution with mean μ= 115 seconds and standard deviation σ = 23 seconds.

a) Use normal probability distribution features of EXCEL to help determine the probability.

Z score (110-115)/23 = -0.21739

P(X < 110) =  22%  Is this correct?

b) If kernel of this brand of popcorn is chosen at random, determine the probability that it will take between 100 seconds and 145 seconds to pop? Shade in the suitable area under given curve to point out required probability of P(100 < X < 145)

I. Z score (100 + 145)/23 =10.65

II. Make use of normal probability distribution features of EXCEL to help determine the probability.

The area to shade will be between 100 and 145 below the curve.

P(100 < X < 145) = ______?_______