9(x + 8) + 11(3x + 4)
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Answer:
6.7% of children who finished the race in under 45 seconds.
Step-by-step explanation:
We are given the following information in the question:
Mean, μ = 75 seconds
Standard Deviation, σ = 20 seconds
We are given that the distribution of time of completion is a bell shaped distribution that is a normal distribution.
Formula:
P(finished the race in under 45 seconds.)
P(x < 45)
Calculation the value from standard normal z table, we have,
6.7% of children who finished the race in under 45 seconds.