Answer:
0.0139
Explanation:
Given that:
The number of sample (n) = 21
The sample distribution has mean (μ) and a standard deviation of σ/√n
The z score is given as (x - mean)/ standard deviation
x = 94.8 wpm, let us assume that σ = 10 and μ = 90
Therefore: z = (x - μ) / (σ/√n) = (94.8 - 90) / (10/√21) = 2.2
To calculate the probability using Z table:
P(X>94.8) = P(Z>94.8) = 1 - P(Z<94.8) = 1 - 0.9861 = 0.0139
The probability is low that is less than 0.05, the program is more effective than the old one.
Ask your teacher about it