Question

A designer uses marbles of four different colours for his designs. The cost of each marble is the same, irrespective of the colour. The table below shows the percentage of marbles of each colour used in the current design. The cost of each marble increased by $25\%.$ Therefore, the designer decided to reduce equal numbers of marbles of each colour to keep the total cost unchanged.

What is the percentage of blue marbles in the new design ?

$\begin{array}{cccc}\text{Blue}& \text{Black}& \text{Red}& \text{Yellow}\\ \text{40\%}& \text{25\%}& \text{20\%}& \text{15\%}\end{array}$

• A.
  $35.75$
• B.
  $40.25$
• C.
  $43.75$
• D.
  $46.25$

Answer 1

The correct option is C

$43.75$
Assume number of marbles = 100

Cost of marbles increased = 25
New cost = Rs. 125
Number of marbles in Rs. 100

$=\frac{100}{125}\times 100=80marbles$
$Now,(40-x)+(25-x)+(20-x)+(15-x)=80$
$100-4x=80$
$x=5$

$\%\text{blue marbles in new design}$
$=\frac{(40-5)}{80}\times 100$
$=35\times \frac{5}{4}=43.75\%$