Question

Find the values of $a$, $b$, $c$ and $d$ in the given cumulative frequency distribution.
$\begin{array}{ccc}x& frequency& Cumulativefrequency\\ 10& 3& a=----\\ 15& 10& b=----\\ 20& 25& c=----\\ 25& 7& d=----\\ 30& 5& 50\end{array}$

• A.
  $a=3,b=13,c=35,d=42$
• B.
  $a=0,b=10,c=35,d=42$
• C.
  $a=3,b=13,c=28,d=35$
  
• D.
  $a=3,b=13,c=38,d=45$

Answer 1

The correct option is D

$a=3,b=13,c=38,d=45$
As cumulative frequency is the sum of all previous frequencies up to the current point,

$\begin{array}{ccc}x& frequency& Cumulativefrequency\\ 10& 3& a=3\\ 15& 10& b=10+3=13\\ 20& 25& c=13+25=38\\ 25& 7& d=38+7=45\\ 30& 5& 45+5=50\end{array}$