Two groups of students, whose average ages are
15 years and 25 years, combine to form a third
group whose average age is 23 years. What is the
ratio of the number of students in the first group
to the number of students in the second group?
Answers
Answer:
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Step-by-step explanation:
Two groups of students, whose average ages are 15 yrs and 25 yrs, combine to form a third group whose average age is 23 yrs. What is the ratio of the number of students in the first group to the number of the second group?
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Two groups of students, whose average ages are 15 yrs and 25 yrs, combine to form a third group whose average age is 23 yrs
Let the number of students in two groups be x and y.
We know average = total sum of ages students / no. of students
Total sum of ages student = average x no.if students
Total sum of ages for group A = 15 × x= 15x
Total sum of ages fir group B = 25×x = 25x
Total sum of ages for both group = 15x + 25x
Total no of students in both group = x + y
Now average age of combined A and B group= total sum of ages if both group / ,total number of students. As such
(15x + 25y) / (x + y) = 23
Cross multiplication
15x + 25y = 23x + 23y
23x + 23y = 15x + 25y
23x - 15x = 25y - 23y
8x = 2y
x / y = 2/8
x / y = 1/4
Ratio between number of students of two groups is 1 : 4