mdavidm_531 wrote:The ratio of boys to girls in Class A is 3 to 4. The ratio of boys to girls in Class B is 4 to 5. If the two classes were combined, the ratio of boys to girls in the combined class would be 17 to 22. If Class A has one more boy and two more girls than class B, how many girls are in Class A?
Multiples of 3:4 are:
3:4
6:8
9:12
etc.
Multiples of 4:5 are:
4:5
8:10
12:15
etc.
Scanning the two lists, look for a combination of ratios that satisfies the condition given: the number of boys in A must be one more than the number of boys in B.
Only one combination works: A = 9:12 and B = 8:10.
This combination satisfies all the conditions given in the problem:
Boys in A - Boys in B = 9-8 = 1.
Girls in A - Girls in B = 12-10 = 2.
Boys combined : Girls combined = (9+8) : (12+10) = 17:22.
Thus, girls in A = 12.
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