Question

The compressive strength of samples of cement can be modeled by a normal distribution with a mean of 4,500 kilograms per square centimeter and a standard deviation of 110 kilograms per square centimeter. what is the probability that a sample's strength is less than 4,600 kg/cm2?

Answer 1

P(x<4600) will be obtained as follows:
z-score is given by:
z=(x-μ)/σ
where:
μ-mean
σ-standard deviation
plugging the values in the equation we get:
z=(4600-4500)/110
z=0.91
thus
P(x<4600)=P(z<0.91)=0.8186