IBPS SO Prelims Exam Model Paper 2

GIVEN:

Prize has to be given to two teachers from six teachers present on the stage in which one teacher is sports teacher FORMULA:

Probability of sports teacher not receiving the prize = 1 – (probability of sports teacher receiving the prize) CALCULATION:

Total number of ways prize can be given to any two teachers from 6 teachers = ${}^{6}C_{2}$ = $\frac{(6 \times 5)}{2}$ = 15 Probability of sports teacher receiving the prize: Two persons receiving the prize one (sports teacher) is fixed. The second person can be selected from remaining 5 teachers in 5 ways. Thus, probability = $\frac{5}{15}$ = $\frac{1}{3}$ Probability of sports teacher not receiving the prize = 1 – (probability of sports teacher receiving the prize) = 1 – $\left(\frac{1}{3}\right)$ = $\frac{2}{3}$ ∴ Sports teacher not getting the prize Alternate Method:

Total number of ways prize can be given to any two teachers from 6 teachers = ${}^{6}C_{2}$ = $\frac{(6 \times 5)}{2}$ = 15 Total number of ways sports teacher not getting the prize = ${}^{5}C_{2}$ = 10 ∴ Required probability = $\frac{10}{15}$ = $\frac{2}{3}$