Question

Previous Question:

The mean store for an exit text at an urban high school examination was 68% with a standard deviation of 3. Given these results, what percentage of students fall under the mean?

25%

50%

60%

75%

Using the same data from the question above, what scores will fall within one standard deviation above and one standard deviation below the mean?

	66 to 72
	60 to 74
	65 to 71
	58 to 81

Answer 1

The mean store for an exit text at an urban high school examination was 68% with a standard deviation of 3.

we know,50% of all values of population fall under median of a distribution, and for a normal distribution mean=median=mode, therefore approximately 50% of the values of a normal ditribution fall below mean.

Generally, distribution of scores of a considerably large population is considered to follow normal distribution.

if we consider the score for an exit test to follow normal distribution with mean 68 and SD 3, the percentage of values that fall under mean is 50%.

The standard deviation is a statistic that measures the dispersion of a dataset relative to its mean.

given,standard deviation=3.

one standard deivaition(SD) above mean implies

mean+1*standard deviation = 68+3 =71

2 standard deivaition above mean implies

mean+2*standard deviation = 68+2*3 =74

similarly, one SD below mean implies

mean-1*SD =68-3 =65

so, scores that fall within one standard deviation above and one standard deviation below the mean is values from 65 to 71