Question

A problem of mathematics is given to three students whose

chances of solving the problem are 1/3, 1/4 and 1/5 respectively. The probability that the question will be solved is

• A. 2/3
• B. ¾
• C. 4/5
• D. 3/5

Answer 1

Answer: (D)

3/5

Answer 2

The probabilities of students not solving the problem are $1 - \frac { 1 } { 3 } = \frac { 2 } { 3 } , 1 - \frac { 1 } { 4 } = \frac { 3 } { 4 }$ and $1 - \frac { 1 } { 5 } = \frac { 4 } { 5 }$ .

Therefore the probability that the problem is not solved by any one of them $= \frac { 2 } { 3 } \times \frac { 3 } { 4 } \times \frac { 4 } { 5 } = \frac { 2 } { 5 }$ .

Hence, the probability that problem is solved$= 1 - \frac { 2 } { 5 } = \frac { 3 } { 5 }$.