Denote by $X$ the number of blemished apples in a box. Then $P(X < 4) = P(X = 0) + P(X=1)+P(X=2)+P(X=3)$ $=0.85^{10} + {10 \choose 1} 0.85^9 0.15 + {10 \choose 2} 0.85^80.15^2 + {10 \choose 3} 0.85^70.15^3 \approx 0.9500$
Denote by $X$ the number of blemished apples in a box. Then $P(X < 4) = P(X = 0) + P(X=1)+P(X=2)+P(X=3)$ $=0.85^{10} + {10 \choose 1} 0.85^9 0.15 + {10 \choose 2} 0.85^80.15^2 + {10 \choose 3} 0.85^70.15^3 \approx 0.9500$