Acashier has 30 bills, all of which are $10 or $20 bills. the total value of the money is $460. how many of each type of bill does the cashier have?

There are 14 $10 bills and 16 $20 bills.

Step-by-step explanation:

Let

x = number of $10 bills

y = number of $20 bills

The sum of the value of x and y is $460.

10 x + 20 y = 460   [1]

The sum of x and y is equal to the total number of bills.

x + y = 30

y = 30 - x   [2]

We replace [2] in [1],

10 x + 20 (30 - x) = 460

10 x + 600 - 20 x = 460

-10 x = -140

x = 14

We can get y if we replace this value of x in [2].

y = 30 - 14 = 16

4

step-by-step explanation:

answer: expected value of x = 1.0

step-by-step explanation:

p(x=0) = 0.25

p(x=1) = 0.50

p(x=2) = 0.25

expected value for x = 0×0.25 + 1×0.5 + 2×0.25 = 1.0