Answer
number of pipes $\approx11$ pipes
Work Step by Step
The cross-sectional area of a pipe with a $5~in$ diameter can be calculated using the formula $A=\frac{\pi}{4}d^{2}$.
Where
$d=5in$
So,
$A=\frac{\pi}{4}(5in)^{2}=19.63in^{2}$
And the cross-sectional area of a pipe with a $1.5~in$ diameter can be calculated using the same formula.
Where
$d=1.5in$
So,
$A=\frac{\pi}{4}(1.5in)^{2}=1.77in^{2}$
To find the number of pipes needed, we divide the area of the $5~in$ pipe by the area of the $1.5~in$ pipe. Thus, we have:
number of pipes $=\frac{19.63in^{2}}{1.77in^{2}}=11.09\approx11$ pipes
