Question

The weights of cars, passing over a bridge have a mean of 3,550 pounds and standard deviation of 870 pounds. Use a calculator to find the approximate probability that the weight of a randomly selected car passing over the bridge is more than 4000 pounds

Answer 1

Using the usual notations and formulas,

mean, mu = 3550

standard deviation, sigma = 870

Observed value, X = 4000

We calculate

Z = (X-mu)/sigma = (4000-3550)/870 = 0,5172

Probability of weight below 4000 lbs

= P(X>4000) = P(z>Z) = 1- P(z>0,5172) = 1 - 0,6950 = 0,305

Answer:

Probability that a car randomly selected is OVER 4000

P(X>4000) = 0,305

THE ANSWER IS 30%