Question

the maths scores of a class has a bell shaped with a mean of 433 and a variance of 1800. Determine what percent of the scores are in the interval between 343 and 523

Answer 1

The normal curve looks like a bell-shaped frequency polygon. Because of this property it is sometimes called the bell-shaped curve.

Z = ( 343 - 433 ) /

Z = -2.12

Using the normal distribution table, the value corresponding to z score of -2.12 equals 0.01700. Thus the percent of score above 343 equals 0.5 - 0.01700 i.e. 0.483

Z = ( 523 - 433 ) /

Z = 2.12

Using the normal distribution table, the value corresponding to z score of 2.12 equals 0.98300 Thus the percent of score below 523 equals  0.98300 - 0.5 = 0.483

The percent of the scores in the interval between 343 and 523 = 0.483 + 0.483

The percent of the scores in the interval between 343 and 523 = 0.966