Let us determine how many standard deviations we moved to the right. Let represent that number. Then, since we know the values of these substitute them inside the equation,Originally Posted by pinksapphire168
solving we get . Looking up this value on the distribution table we find that That tells us that approximately 7.1% are above 18 and below 18.5. Thus, since everything is in symettry over here the same applies to above 17.5 and below 18 is also 7.1%. Thus, in total we have approximately 14.2%.
The table which was used can be found at