A Normal distribution has mean µ = 61.6. Find it’s standard deviation if 20% of the values are greater than 70. (Hint--use the z-score formula).

The value is  

Step-by-step explanation:

From the question we are told that

   The mean is

Given that 20% of the values are greater than 70, the z-score to  the right of the curve  corresponding to 20% (0.2) of the values is

Generally this z-score is mathematically represented as

Here  x = 70  

So

=>