You are correct that the number of female sophomores that are studying geometry is equal to $0.2(2f-20) -0.15(f-20)$. However, this is an expression and not an equation and we have nothing to equate this to solve for $f$.
You ended up equating the two expressions to form the following equation $0.2(2f-20) = 0.15(f-20)$, which is what gave you $f=4$, however this equation is equivalent to saying that the number of female sophomores studying geometry is equal to the number of male sophomores studying geometry, which is not the case here. I hope this makes sense.
Hi,
I ran into issue while solving this problem and not sure where I went wrong.
Combining st 1 and 2, let females = f, and males = f-20.
so total no of students= f+f-20=2f-20
total students studying geometry = 0.2(f+f-20) = 0.2(2f-20)
males studying geometry = 0.15(f-20)
so no of females studying geometry is:
0.2(2f-20) -0.15(f-20)
or f= 4
now, i run into problems as females are 4, so males cannot be negative in number.
Where did I go wrong ?
Thanks,
Jayita
Hi Jayita,
You are correct that the number of female sophomores that are studying geometry is equal to $0.2(2f-20) -0.15(f-20)$. However, this is an expression and not an equation and we have nothing to equate this to solve for $f$.
You ended up equating the two expressions to form the following equation $0.2(2f-20) = 0.15(f-20)$, which is what gave you $f=4$, however this equation is equivalent to saying that the number of female sophomores studying geometry is equal to the number of male sophomores studying geometry, which is not the case here. I hope this makes sense.