Answer:
2 4
- _
8 16
Step-by-step explanation:
1 2
- X -
4 2
Or
1. 4
- X -
4. 4
5miles/8km = xmiles/80km
8x=400
x=50
B. 54
Because 54+13=67
67+54=121
We are given:

Our goal in solving for any variable, in this case is x, we need to isolate x on one side of the variable. Let's start by subtracting 7x from both sides, which will cancel the +7x on the right side. We are then left with:

Now, we want to move that +10 to the other side so our x is all by itself. Let's subtract 10 from both sides, which will cancel the +10 on the right leaving us with:

Since we cannot have a coefficient when solving for x, we need to divide both sides by -3.

When we divide, our answer is:

Answer:
a) 

And we want the probability from 0 to two deviations above the mean and we got 95/2 = 47.5 %
b) 

So one deviation below the mean we have: (100-68)/2 = 16%
c) 

For this case below 2 deviation from the mean we have 2.5% and above 1 deviation from the mean we got 16% and then the percentage between -2 and 1 deviation above the mean we got: (100-16-2.5)% = 81.5%
Step-by-step explanation:
For this case we have a random variable with the following parameters:

From the empirical rule we know that within one deviation from the mean we have 68% of the values, within two deviations we have 95% and within 3 deviations we have 99.7% of the data.
We want to find the following probability:

We can find the number of deviation from the mean with the z score formula:

And replacing we got


And we want the probability from 0 to two deviations above the mean and we got 95/2 = 47.5 %
For the second case:


So one deviation below the mean we have: (100-68)/2 = 16%
For the third case:

And replacing we got:


For this case below 2 deviation from the mean we have 2.5% and above 1 deviation from the mean we got 16% and then the percentage between -2 and 1 deviation above the mean we got: (100-16-2.5)% = 81.5%