Answer with explanation:
Mean of the Data set which is Normally Distributed =84
Standard Deviation =2.5
Data values which lie within one standard Deviation that is between , (84-2.5=81.5) to (84+2.5=86.5) is given by
.
Which states that 68% of the data lie between one standard deviation ,that is between values 81.5 to 86.5 of all variate.