Question

Directions: Draw a clearly labeled diagram and then solve each problem.

8. The mean pulse rate for adults is 72 beats per minute (www.healthepic.com) and let’s suppose that the standard deviation is 10. Find:

a. The probability that a randomly chosen adult has a pulse rate over 78 assuming that the rates are normally distributed.

2. The probability that a random sample of 19 adults will have a mean score over 78.

Answer 1

solution

(a)P(x > 78) = 1 - P(x<78 )

= 1 - P[(x -) / < (78 -72) /10 ]

= 1 - P(z <0.6 )

Using z table

= 1 - 0.7257

=0.2743

probability=0.2743

(b)

n = 19

= 72

= / n = 10/ 19 = 2.2942

P( >78 ) = 1 - P( < 78)

= 1 - P[( - ) / < (78 -72) /2.2942 ]

= 1 - P(z <2.62 )

Using z table

= 1 - 0.9956

= 0.0044

probability= 0.0044