Ok this i do not get at all - empirical rule? normal standard curve? please help me :(?

The left-hand "tail" of the standard normal curve can be defined as the part of it that lies at least two standard deviations to the left of the mean.

According to the Empirical Rule, approximately what percentage of the area under the whole curve is in the left-hand tail? Round your answer to the nearest tenth.

Question

Ok this i do not get at all - empirical rule? normal standard curve? please help me :(?

The left-hand "tail" of the standard normal curve can be defined as the part of it that lies at least two standard deviations to the left of the mean. 

According to the Empirical Rule, approximately what percentage of the area under the whole curve is in the left-hand tail? Round your answer to the nearest tenth.