Depends on what time their bedtime is, like if their bedtime is at 6:00, and they have to wake up at 5:00 then their waking hours would be 11 hours.
Given:
1 - 50 written in red marker
51 - 100 written in blue marker
Probability of selecting a number greater than 81; 100 - 81 = 19 possible numbers. 1 draw. 1/19
Probability of selecting a number written in red: 1/50
Probability of selecting a number written in blue: 1/50
Probability of selecting a number that is a multiple of 10. There are 10 instances; 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 ; 1/10
Answer:
The probability that the instrument does not fail in an 8-hour shift is 
The probability of at least 1 failure in a 24-hour day is 
Step-by-step explanation:
The probability distribution of a Poisson random variable X representing the number of successes occurring in a given time interval or a specified region of space is given by the formula:

Let X be the number of failures of a testing instrument.
We know that the mean
failures per hour.
(a) To find the probability that the instrument does not fail in an 8-hour shift, you need to:
For an 8-hour shift, the mean is 

(b) To find the probability of at least 1 failure in a 24-hour day, you need to:
For a 24-hour day, the mean is 

The answer is £140
First you find 20% of 1200 (which is basically 20 times 12) which gives you £240.
You add £240 to £1200 which is £1440
Then you take £300 off £1440 since he already paid the deposit.
That leaves you with £1140
1140 divided by 10 is 114