The time (X) to complete a standardized exam is approximately normal with a mean of 70 minutes and standard deviation of 10 minu tes. How much time should be given to complete the exam so that 80% of the students will complete the exam in the time given?
1 answer:
Answer:
77.88 minutes
Step-by-step explanation:
Given that :
Mean (m) = 70
Standard deviation (s) = 10
For 80% of student to complete the exam. In the given time
Using the formula :
Zscore = (X - mean) / standard deviation
80th percentile = 80/100 = 0.8 has a Zscore = 0.7881
0.7881 = (X - 70) /10
0.7881 * 10 = X - 70
7.881 = X - 70
7.881 + 70 = X
77.881 = X
Hence, 77.88 minutes should be given
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