Answer: the probability it will come up heads 25 or fewer times is 0.019
Step-by-step explanation:
Given that;
n = 50
p = 0.65
so, q = 1 - p = 0.35
np = 50 × 0.65 = 32.5 ≥ 10
nq = 50 × 0.35 = 17.5 ≥ 10
so, we need to use Normal Approximation for the Binomial Distribution
μ = np = 50 × 0.65 = 32.5
σ = √(npq) = √( 50 × 0.65 × 0.35 ) = 3.3726
now, the probability that it will come up heads 25 or few times will be;
⇒ P( x≤25)
{using continuity correction}
⇒ P[ z < (25.5 - 32.5)/3.3726 ]
⇒ P[ z < -2.0755 ]
using z-table
= 0.01923 ≈ 0.019 { 3 decimal places}
Therefore the probability it will come up heads 25 or fewer times is 0.019
