Question

1) The set of the weights of professional football players was found to have a mean of 275 lbs.

with a standard deviation of 15 lbs. If there are a total of 1,650 pro football players in the

US, what is the minimum number that weigh between 250 and 300 lbs.?

2) Scientists measured the area claimed by each Bengal tiger in a certain jungle. The mean

area claimed was 30 square miles with s=2.8 mi2. At least 99% of the areas in this sample

would have to be between _________ and ________ mi2

3) 400 books were selected at random from a library. If the mean length of books in this sample was 300 pages with s=20, what is the minimum number of books that must be between 200 and 400 pages?

4) The length of human pregnancies from conception to birth is normally distributed with mean 266 days and standard deviation 16 days. Use the 68-95-99.7 rule to estimate the following:

• The proportion of the lengths of pregnancies that fall between 250 days and 282 days.

• The middle 95% of the lengths of all pregnancies fall between which two values?

• How short must the length of a pregnancy is for it to fall in the shortest 2.5% of all

  human pregnancies?

• How long must the length of a pregnancy is for it to fall in the longest 2.5% of all human pregnancies?

5) Heights of male adults in the United States are normally distributed with mean 69.1 inches and standard deviation 2.7 inches. Use the 98-95-99.7 rule to estimate the following:

a) The proportion of male adults whose height is between 66.4 inches and 74.5 inches

b) The proportion of male adults whose height is between 61.0 inches and 71.8 inches.

c) The proportion of male adults whose height is between 69.1 inches and 77.2 inches.

6) Heights of female adults in the United States are normally distributed with mean

inches and standard deviation 2.5 inches. If the proportion of female adults who

are shorter than 67 inches is 0.84, determine H.

Answer 1

Civen hat mean 21S 250 21S 300-2tS > 15 - 1.661 1.66 chutyla's mepully mply Foom c X100 (- हेस्) 2. 1-66) 6401 tolal ot 1650 pao f ball 1650 O.6401 1056 2 31 t0s6 ০.৭৭ 1- I K100 kt10 0.01 X-30 X-30 -10 = 2-F X : 58 5& and batioeen 2