The probability of a shooter of hitting the target is $\frac{1}{4}$. The minimum number of fire needed so that the probability of hitting the target atleast once is greater than $\frac{7}{16}$ is: |
1 2 3 4 |
3 |
The correct answer is Option (3) → 3 Given: Probability of hitting target in one shot: $p = \frac{1}{4}$ Probability of missing target in one shot: $q = 1 - p = \frac{3}{4}$ Let $n$ = number of shots. Probability of hitting target at least once: $P(\text{at least one hit}) = 1 - q^n = 1 - \left(\frac{3}{4}\right)^n$ Set inequality: $1 - \left(\frac{3}{4}\right)^n > \frac{7}{16}$ $\left(\frac{3}{4}\right)^n < 1 - \frac{7}{16} = \frac{9}{16}$ Check powers of $3/4$: $\left(\frac{3}{4}\right)^1 = 3/4 = 12/16 > 9/16$ → not enough $\left(\frac{3}{4}\right)^2 = 9/16 = 9/16$ → equal, need > → not enough $\left(\frac{3}{4}\right)^3 = 27/64 \approx 0.4219 < 9/16 = 0.5625$ → satisfies Hence, minimum $n = 3$ |