Four buses carrying 146 high school students arrive to montreal. the buses carry, respectively, 32, 44, 28, and 42 students. one of the studetns is randomly selected. let x denote the number of students that were on the bus carrying this randomly selected student. one of the 4 bus drivers is also randomly selected. let y denote the number of students on his bus. compute the expectations and variances of x and y

The expected value of X is and the variance of X is

The expected value of Y is and the  variance of Y is

Step-by-step explanation:

(a) Let X be a discrete random variable with set of possible values D and  probability mass function p(x). The expected value, denoted by E(X) or , is

The probability mass function of X is given by

Since the bus driver is equally likely to drive any of the 4 buses, the probability mass function of Y is given by

The expected value of X is

The expected value of Y is

(b) Let X have probability mass function p(x) and expected value E(X). Then the variance of X, denoted by V(X), is

The variance of X is

The variance of Y is

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!

i think it would be c

mark brainliest if im right

step-by-step explanation: