Question

Am i right that the answer is C

If 2/5 of a ton of concrete covers 5/6 of a wall, how many tons of concrete are required to cover the entire wall?

12/25 ton
3/5 ton
1 and 7/30 tons
2 and 1/12 tons

Answer 1

No..that is incorrect.

Answer 2

how

Answer 3

it would be a i see what i did wround

Answer 4

Just divide them.

\(\sf \dfrac{2}{5} \div \dfrac{5}{6}\)

FLip the 2nd fraction and multiply:

\(\sf \dfrac{2}{5} \times \dfrac{6}{5}\)

Can you multiply?

Answer 5

Yep, A is correct..

\(\sf \dfrac{2}{5} \times \dfrac{6}{5} \rightarrow \dfrac{2\times 6}{5\times 5} \rightarrow \dfrac{12}{25}\)

Answer 6

thxs for your help

Answer 7

one way to figure out what to do is think "ratio"
2/5 ton "is to" 5/6 wall "as" x tons "is to" 1 wall

(notice 2/5 "goes with" 5/6 of a wall, and we want x (for unknown) "goes with" 1 full wall

write the ratio as fractions:
\[ \frac{ \frac{2}{5}}{\frac{5}{6}} = \frac{x}{1} \]
of course x/1 is just x so the problem is
\[ x= \frac{ \frac{2}{5}}{\frac{5}{6}} \]

Answer 8

to simplify the messy fraction, use the idea that you can multiply top and bottom by the same number. in this case , use 6/5, like this
\[ x= \frac{ \frac{2}{5}\cdot \frac{6}{5}}{\frac{5}{6}\cdot \frac{6}{5}} \]

notice that 5/6 * 6/5 is 1, so you have
\[ x=\frac{ \frac{2}{5}\cdot \frac{6}{5}}{1} \\
x= \frac{2}{5}\cdot \frac{6}{5}
\]

Answer 9

some people remember that you can change divide to multiplying by first "flipping" the bottom number. so the fast way is to remember that
\[ x= \frac{ \frac{2}{5}}{\frac{5}{6}} = \frac{2}{5} \cdot \frac{6}{5} \]