First, you need to make the fractions have the same denominator:
15 1/2 ---> 15 + (1/2 x 5) = 15 5/10
2 1/10 ---> 2 1/10
Then you need to subtract them from each other:
15 5/10
<u>- 2 1/10</u> (or) 15 5/10 - 2 1/10 = 13 4/10
13 4/10
This gets the answer: <u>13 4/10</u>
Presuming the question is "How many points did he miss", you would find the solution by multiplying the amount of possible points by the test score as a fraction. 96% is the fraction

. Therefore, you get the equation

. This is equal to 72, so he missed 3 points, or 75-72 points.
He missed 3 points.
95% of red lights last between 2.5 and 3.5 minutes.
<u>Step-by-step explanation:</u>
In this case,
- The mean M is 3 and
- The standard deviation SD is given as 0.25
Assume the bell shaped graph of normal distribution,
The center of the graph is mean which is 3 minutes.
We move one space to the right side of mean ⇒ M + SD
⇒ 3+0.25 = 3.25 minutes.
Again we move one more space to the right of mean ⇒ M + 2SD
⇒ 3 + (0.25×2) = 3.5 minutes.
Similarly,
Move one space to the left side of mean ⇒ M - SD
⇒ 3-0.25 = 2.75 minutes.
Again we move one more space to the left of mean ⇒ M - 2SD
⇒ 3 - (0.25×2) =2.5 minutes.
The questions asks to approximately what percent of red lights last between 2.5 and 3.5 minutes.
Notice 2.5 and 3.5 fall within 2 standard deviations, and that 95% of the data is within 2 standard deviations. (Refer to bell-shaped graph)
Therefore, the percent of red lights that last between 2.5 and 3.5 minutes is 95%
The correct answer is C. 2,836
when 2836 is divided by 2 it equals 1418. when it is divided by 4 it equals 709. 709 is a whole number, therefore it is correct, and can be divided by both 2 and 4.