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How to find the average of these ages of people?
The question is: Express the average age of three sisters in the terms of the age "a" of the firstborn (in years) if the second was born "4" years after the first and the third was born "3" years after the second.
The answer i got was (3a + 11)/3 but it said it was incorrect.
3 Answers
- OleyLv 41 decade agoFavorite Answer
If the second sister was born 4 years after the first, her age would (a - 4), and the third sister's age would be (a - 7).
Adding all three, gives you a + (a - 4) + (a - 7) which equals 3a - 11.
The average would then be (3a - 11)/3
- gjakeLv 41 decade ago
a = age of firstborn
a-4 = age of 2nd
a-4-3 = a-7 = age of 3rd
so the average age would be...
(a + a-4 + a-7)/3
= (3a -11)/3
