Ashipment of beach balls with a mean diameter of 28 cm and a standard deviation of 1.3 cm is normally distributed. by how many standard deviations does a beach ball with a diameter of 31.9 cm differ from the mean?

31.9 cm differs from mean by 3 standard deviations.

Step-by-step explanation:

Given:

Mean diameter of the ball = 28 cm

Standard deviation = 1.3 cm

Thus the number of standard deviations by which 31.9 cm ball size differs from the mean ball size is given by the standard normal deviate (Z) given by

Applying values we get

Thus 31.9 cm differs from mean by 3 standard deviations.

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step-by-step explanation:

hopefully im right