Question

I've had problems understanding situations involving the mixture of substances that are already in a ratio. I can't work with two or more ratios. Here's an example sum that fails me - "There are three containers of equal capacity and all are completely filled with acid and water mixtures in different ratios. The ratio of acid to water in the first container is 2:3, in the second container is 3:7 and in the third container it is 4:11. If the mixtures of all the three containers are mixed together, what is the ratio of acid to water in it?"

Answer 1

since you are not told the amount in each, a nice gimmick to use is to pick a number, compute with that number, and then since the number is unimportant, the answer will be correct

Answer 2

i would pick the least common multiple of 3, 7 and 11, which is 231

Answer 3

then \(\frac{2}{3}\times 231 =154, \frac{3}{7}\times 231=99, \frac{4}{11}\times 231=84\)

Answer 4

But the answer is 29/61

Answer 5

I'll try to explain my method

Answer 6

the 3 ratios given are 2:3, 3:7 and 4:11

Based on each ratio, add them up to find the total composition of each ratio

That would give 5, 10 and 15

Scale these numbers to a common multiple. 30 is good. so, multiply the first ratio by 6, the second by 3 and the thord by 2

Answer 7

that would make the three ratios as 12:18, 9:21 AND 8:22

Answer 8

add the components of the acid and water from the three ratios

Answer 9

you get 29:61

Answer 10

oh yeah i am way off sorry

Answer 11

it is five parts, ten parts and 15 parts, not what i wrote

Answer 12

so make them all 30 parts as said above

Answer 13

Irkiz thanks a lot