Probability Problems '- Sample 3 Worksheet With Answers (Page 3 of 4) in pdf

Probability Problems '- Sample 3 Worksheet With Answers Page 3

Answers to the Above Questions

a) Let x be the number of people with both high blood

pressure and high level of cholesterol. Hence (15 - x) will

be the number of people with high blood pressure ONLY

and (25 - x) will be the number of people with high level of

cholesterol ONLY. We now express the fact that the total

number of people with high blood pressure only, with high

level of cholesterol only and with both is equal to 30.

(15 - x) + (25 - x) + x = 30

solve for x: x = 10

b) 15 have high blood pressure,hence P(A) = 15/40 =

0.375

c) 25 have high level of cholesterol, hence P(B) = 25/40 =

0.625

d) 10 have both,hence P(A and B) = 10/40 = 0.25

e) 30 have either, hence P(A or B) = 30/40 = 0.75

e) P(A) + P(B) - P(A and B) = 0.375 + 0.625 - 0.25 = 0.75

= P(A or B)

a) x = 80 , z = (80 - 70)/10 = 1

Probablity for grade to be greater than 80 = 1 - 0.8413 =

0.1587

b) x = 50 , z = (50 - 70)/10 = -2

Probablity for grade to be less than 50 = 0.0228

c) The z-scores for x = 50 and x = 80 have already been

calculated above.

Probablity for grade to be between 50 and 80 = 0.8413 -

0.0228 = 0.8185

d) 0.1587 * 1000 = 159 (rounded to the nearest unit)

Probability Problems '- Sample 3 Worksheet With Answers Page 3