Because 50% of something means half (because 100-50=50), he would have to make the number of girls and boys equal. Since there are 21 girls, he has to make it so there are also 21 boys.
So, if we know that 21-15=6, this means he would have to add 6 boys to the club if he wants the girls and boys equal.
Given that height, h(t) of a tennis ball is modeled by the equation h(t)=<span>-16t^2 + 45t + 7, the time taken for the ball to reach maximum height will found as follows:
at maximum height:
h'(t)=0
but from the equation:
h'(t)=-32t+45=0
solving for t we get
t=45/32
t=1.40625~1.4 seconds
Thus the time taken to reach maximum height is 1.4 seconds
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