In problem 4 assume that a room contains 30 children of whic

In problem 4. assume that a room contains 30 children of which 20 are girls and 10 are boys selected at random, one at a time, and taken to another room for a reading test. 4. Find the probability that at least two boys will be selected. A group of three children v, 5. The percentage of KU freshman students who study intensively for English I is 70%. Of the KU freshman students who study intensively for English I, 75% pass the course. Of the KU freshman students who do not study intensively, only 30 /0 pass English I. a. Find the percentage of KU freshman students who study intensively for English I and also pass the course. b. Find the percentage of KU freshman students who do not study intensively for English I and do not pass the course. c. Find the percentage of KU freshman students who do not pass English I.

Solution

P(atleast two boys) =1- p(no boys) - P(1 boy) = 1- (20 C 3 / 30 C 3) - (20 C 2* 10 C 1/ 30 C 3) = 1-0.28- 0.15 = 0.56

2 a students who study intensively and pass = % who study intensively * % who pass when studying intensively = 0.7*0.75 = 0.525 = 52.5%

b students who didnot study intensively and didnt pass = % didnt study intensively * % didnt pass if didnt studdy intensively = 0.3* 0.7 =0.21 = 21%

c % who donot pass = % who dont pass studying intensively + % who donot pass studying non intensively = 0.7 * 0.25 + 0.3*0.7 = 0.385 = 38.5%