Three friends went to lunch. they all ordered the same meal. at the end of lunch they gave the waiter a $12 tip.

a. write a algebraic expression to represent the situation.

b. how much total money was spent if each meal cost $7.50?

2, 0.135, 0.270, 0.270, 0.180, 0.145

Step-by-step explanation:

1. To calculate the mean of people arriving in 5 minute period:

We know the arrival rate of minute is 0.4, so people arriving in 5 minutes will be

0.4 x 5 = 2

2. From part 1 it is known thay mean arrival time=2

For this we will use poisson's probability formula that is

P(X=x) = (2^x) x Exp^(-2/x!)

For X=0

P(X=0) = (2^0) x Exp^(-2/0!) = 0.135

For X = 1

P(X=1) = (2^1) x Exp^(-2/1!) = 0.270

For X = 2

P(X=2) = (2^2) x Exp^(-2/2!) = 0.270

For X = 3

P(X=3) = (2^3) x Exp^(-2/3!) = 0.180

3. For delay expected if more than 3 customer arrive in 5 minutes.

P(X>3) = 1 - P(X=0) - P(X=1) - P(X=2) - P(X=3)

P(X>3) = 1-0.135-0.270-0.270-0.180

P(X>3) = 0.145