Answer:
0.52763 is the probability that the time between the next two calls will be 54 seconds or less.
0.19285 is the probability that the time between the next two calls will be greater than 118.5 seconds.
Step-by-step explanation:
We are given the following information in the question:
The time between telephone calls to a cable television service call center follows an exponential distribution with a mean of 1.2 minutes.
The distribution function can be written as:

The probability for exponential distribution is given as:

a) P( time between the next two calls will be 54 seconds or less)

0.52763 is the probability that the time between the next two calls will be 54 seconds or less.
b) P(time between the next two calls will be greater than 118.5 seconds)

0.19285 is the probability that the time between the next two calls will be greater than 118.5 seconds.
This is a problem of guess and check; there's no easier way to do it.But in this case you must have an odd number of nickels to make the 5 cents, so your answer is 9 nickels.you can check this by multiplying each one by .05:
9*.05=.45
the rest of the coins left, are 8 of them, and their dimes.
.10*8=.80
.80+.45= 1.25
Answer:
He received $6.40 in change.
Explanation:
Since he bought 2.25 pounds, you multiply that by 1.6 to get a sum of 3.6. Since he paid with a ten dollar bill, and he only has to pay 3.60, they will give him back 6.40 in change.
Hope this helped :)
The problem is that 7^2 is 7*7, and the same for 8^2. The right answer is the square root of 15, or 3.87