Question

John's bag contains a total of $10$ marbles of blue, white and red color. Find the number of white marbles in the bag if the number of blue and red marbles are $4$ and $3$ respectively.

• A. $2$
• B. $3$
• C. $4$
• D. None of the above

Answer 1

The correct option is B $3$

$\underset{–}{\text{Given:}}$
Total number of marbles in John's bag $=10$
Number of blue marbles $=4$
Number of red marbles $=3$

$\underset{–}{\text{Need to Find:}}$
Number of white marbles in John's bag.

Let the number of white marbles be $w.$

Now, according to the question:

No. of blue marbles $+$ No. of white marbles $+$ No. of red marbles $=$ Total no. of marbles in the bag

$\Rightarrow 4+w+3=10$

$\Rightarrow w+7=10$

$\Rightarrow w+7-7=10-7$
(subtracting 7 from both sides)

$\Rightarrow w=3$

$\therefore$ The number of white marbles in John's bag is $3.$

Hence, option (b) is the correct choice.