52 % of 825 = ( 52 / 100 ) * 825 = 52 * 825 / 100 = 42900 / 100 = 429 boys
When more boys joined the school numbers of boys will be:
429 + x
total number of pupils will be 825 + x
( 429 + x ) / ( 825 + x ) = 64 % = 64 / 100 = 0.64
( 429 + x ) / ( 825 + x ) = 0.64 Multiply both sides by 825 + x
429 + x = 0.64 * ( 825 + x )
429 + x = 0.64 * 825 + 0.64 * x
429 + x = 528 + 0.64 x Subtract 0.64 x to both sides
429 + x - 0.64 x = 528 + 0.64 x - 0,64 x
429 + 0.36 x = 528 Subtract 429 to both sides
429 + 0.36 x - 429 = 528 - 429
0.36 x = 99 Divide both sides by 0.36
x = 99 / 0.36 = 275 boys
Proof:
When 275 boys joined the school numbers of boys will be 429 + 275 = 704 boys
Total number of pupils will be 825 + 275 = 1100 pupils
704 / 1100 = 0.64 = 64 %
there were 825 pupils in a school. 52 percent were boys. more boys joined the school and the percentage of boys became 64 percent of the new total. how many boys joined the school?
1 answer