A class has 250 students. The distribution of the students' mark percentage in the last test follows the normal distribution with mean and standard deviation is 56.5% and 11.2% respectively. i. Find the percentage of students' score lie between 70% and 80%. ii. Find the percentage of students kept more than 90%. iii. Find the percentage value for 45 percentile
Added by Richard B.
Step 1
The z-score is calculated as (X - μ) / σ, where X is the score, μ is the mean, and σ is the standard deviation. So, the z-scores for 70% and 80% are (70 - 56.5) / 11.2 = 1.21 and (80 - 56.5) / 11.2 = 2.10 respectively. Looking these z-scores up in a standard Show more…
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