4. The numbers $p, q, r$ and $s$ satisfy the equations $p=2, p \times q=20, p \times q \times r=202$ and $p \times q \times r \times s=2020$.
What is the value of $p+q+r+s$ ?
A 32
B 32.1
C 33
D 33.1
E 34
Solution
B
We have
$$
\begin{array}{l}
p=2, \\
q=\frac{p \times q}{p}=\frac{20}{2}=10, \\
r=\frac{p \times q \times r}{p \times q}=\frac{202}{20}=10.1,
\end{array}
$$
and
$$
s=\frac{p \times q \times r \times s}{p \times q \times r}=\frac{2020}{202}=10 \text {. }
$$

Therefore $p+q+r+s=2+10+10.1+10=32.1$.