Answer:
The standard deviation of car age is 2.17 years.
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
68% of the measures are within 1 standard deviation of the mean.
95% of the measures are within 2 standard deviation of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean = 7.5
(a) If 99.7% of the ages are between 1 year and 14 years, what is the standard deviation of car age?
This means that 1 is 3 standard deviations below the mean and 14 is 3 standard deviations above the mean.
So

I want to find 



The standard deviation of car age is 2.17 years.
Answer: see the graphic
Step-by-step explanation:
A. Type I error helps us to conclude that the flight is not profitable, when in fact it is profitable.
B. a = 0.05
C. Type II error does not show that the flight is profitable
Answer:
16 years
Step-by-step explanation:
Let x represent the number of years. The suburb population is growing at a rate of 5000 per year after x years, it can be represented by the equation:
320000 + 5000x
The city population is declining at a rate of 14000 per year after x years, it can be represented by the equation:
624000 - 14000x
The number of years for the city and suburb population to be equal can be gotten from:
320000 + 5000x = 624000 - 14000x
14000x + 5000x = 624000 - 320000
19000x = 304000
x = 304000 / 19000
x = 16
In 16 years the populations of the suburb and the city be equal
Answer:

Step-by-step explanation:
Let
represent the cost of the torch and
represent the cost of the battery.
The torch and a battery cost £2.50 altogether.

The torch costs £2.00 more than the battery.

We substitute the second equation into the first equation to get;


£2.50


The price of the battery is £0.25
We express this as a fraction of the total cost which is £2.50 to get;
