Answers:
(a) 19:43
(b) 24:43
(c) 19:24
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Work Shown for Part (a)
418 girls : 946 total
418:946
418/22 : 946/22
19:43
Note: 22 is the GCF of 418 and 946
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Work Shown for Part (b)
946 total students, 418 are girls, the remaining 946-418 = 528 are boys
528:946
528/22 : 946/22
24:43
Note: 22 is the GCF of 528 and 946
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Work Shown for Part (c)
418 girls : 528 boys
418:528
418/22 : 528/22
19:24
Another approach: The result of part (a) tells us there could be 19 girls in a class of 43 students. The result of part (b) tells us there are 24 boys in a class of 43 students. Note that 19+24 = 43.