A) 6
Replace the y with 6
4(6)+13=37
Multiply
24+13=37
Add
37=37
I hope this helps :)
If you have any questions about my answer please feel free to ask:)
Answer:
0.1353 = 13.53% probability that the lifetime exceeds the mean time by more than 1 standard deviations
Step-by-step explanation:
Exponential distribution:
The exponential probability distribution, with mean m, is described by the following equation:

In which
is the decay parameter.
The probability that x is lower or equal to a is given by:

Which has the following solution:

The probability of finding a value higher than x is:

The mean time for the component failure is 2500 hours.
This means that 
What is the probability that the lifetime exceeds the mean time by more than 1 standard deviations?
The standard deviation of the exponential distribution is the same as the mean, so this is P(X > 5000).

0.1353 = 13.53% probability that the lifetime exceeds the mean time by more than 1 standard deviations
The answer is 6 and 1/15.
The answer is a vertical line on the negative -2 (x-axis).