math
posted by Malena .
I am so bad at word problems! Help me find out how to figure this one out.
1/5 of the boys are absent and 2/5 of the girls are absent in Drew’s class. Bert thinks that you multiply, so his answer is 2/5 of the class are out. Elmo thinks that means 3/5 of the class is out. Ernie thinks 3/10 of the class is out. Kermit didn’t find out how much of the class are out, but he thinks the answer is between 1/5 and 2/5. Analyze each person’s answer to find out who is right. Then determine who knows the most math.

absent: b/5 + 2g/5
= (b+2g)/5
fraction absent = (b+2g)/(5b+5g)
...going nowhere
take an example,
suppose there are 25 boys and 30 girls or 55 total
boys missing = 5
girls missing = 12
total missing = 17
fraction missing = 17/55
which is none of 2/5, 3/5, or 3/10
now 1/5 = 11/55
and 2/5 = 22/55
mmmh? 
Elmo is correct because 1/5+2/5=3/5.