The average weight of 30 students is x kg and the average weight of another 30 students is y kg. The ratio of x and y is 2:3. Find the average weight of the total students.

I tried:

\(\displaystyle \frac {30(X) + 30(Y)}{X+Y}\)

$\frac {X}{Y}$= \(\displaystyle \frac{2}{3}\)

X = \(\displaystyle \frac {2Y}{3}\)

\(\displaystyle \frac {30(\frac {2}{3})Y + 30Y}{\frac {2}{3}Y+Y}\)

\(\displaystyle 3 \frac{20Y+30Y}{2Y+3Y}\)

\(\displaystyle 3(10) \frac{5y}{5y}\)

= 30

But answer is \(\displaystyle \frac {X+Y}{2}

\)

I tried:

\(\displaystyle \frac {30(X) + 30(Y)}{X+Y}\)

$\frac {X}{Y}$= \(\displaystyle \frac{2}{3}\)

X = \(\displaystyle \frac {2Y}{3}\)

\(\displaystyle \frac {30(\frac {2}{3})Y + 30Y}{\frac {2}{3}Y+Y}\)

\(\displaystyle 3 \frac{20Y+30Y}{2Y+3Y}\)

\(\displaystyle 3(10) \frac{5y}{5y}\)

= 30

But answer is \(\displaystyle \frac {X+Y}{2}

\)

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