Question

There are 13 marbles, out of which 6 are red, and the rest are blue. How many blue marbles are there?

• A. 5
• B. 6
• C. 8
• D. 7

Answer 1

The correct option is D 7

$\text{Detailed step-by-step solution:}$
Total number of marbles = 13
Number of red marbles = 6
Number of blue marbles = 13 − 6
We count back from 13 till 10 on the number line. The numbers we count are 12, 11, 10, i.e. 3 numbers.
So, counting 3 more from 10—9, 8, 7.
13 − 6 = 7


Hence, there are 7 blue marbles.