So 15 gallons of gas brought it from 1/8 full to 3/4 full.

Let's change 3/4 to the equivalent fraction 6/8 so that the denominators are the same. (3/4 = 6/8)

So 15 gallons of gas brought it from 1/8 to 6/8 Those 15 gallons must be 5/8 of the tank's capacity 6/8 - 1/8 = 5/8

So 15 is 5/8 of what number? (This will tell us the capacity of the whole tank)

15 = 5/8n
Divide both sides by 5/8 (remembering to multiply by the reciprocal 8/5)
15 ÷ 5/8 = 15 x 8/5 = 18

So the tank holds 24 gallons and (since it is 3/4 full or has 18 gallons) it needs 6 gallons to fill the tank.

Check - at first 1/8 full (1/8 of 24 = 3) So we started with 3 gallons. 15 gallons added to the 3 gallons is 18 gallons. Now the tank is 6/8 (3/4 full). The remaining 1/4 (2/8) of a tank is the difference between 18 and it's capacity (24 gallons) so it will need 6 gallons to fill it up..

3 0

2 years ago

Heidi has an average score of 78 for her first six chemistry tests. If Heidi"s scores for the first four tests were 82,78,87, an

elixir [45]

Answer:

(A)74

Explanation:

Let her average score on the last two tests = x.

The six scores will now be: 82,78,87,73, x and x.

Since the average score for her first six chemistry tests = 78

$\frac{82+78+87+73+x+x}{6}=78$

We then solve for x.

$\begin{gathered} 320+2x=78\times6 \\ 320+2x=468 \\ 2x=468-320 \\ 2x=148 \\ x=\frac{148}{2} \\ x=74 \end{gathered}$

Her average score for the last two tests is 74.

3 0

1 year ago