Answer:
We know that the total area under the normal curve is 100%. According to the empirical rule of Normal distribution:
Approximately, 68% of data lies within standard deviations of mean.
Approximately, 95% of data lies within standard deviations of mean.
Approximately, 99.7% of data lies with standard deviations of mean,
Therefore, in a normal curve, roughly 95% of all cases fall within plus or minus two standard deviations.