A grocery store estimates that customer arrive at the rate of 15 per hour. the cashier can servce customers at a rate of 20 per hour calculate the average number of customers in a line

2.25

Step-by-step explanation:

let: Mean arrival rate and mean service rate

#First  we need to calculate the average number of customers in the system and average  time a customer spends in the system, as:

The average time spend in the line is:

Hence  the average number of customers in a line is 2.25

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!