Find the number 1.5 standard deviations below the mean?

Question

x Frequency

0 2

1 15

2 32

3 29

4 10

5 9

6 3

This has me stumped so hard... I need to round the answer to 3 decimal points as well.

Answer 1

Compute the mean using the formula: sum (f(i)* x(i))/ sum(f(i)), where i = 0 to 6

Compute the variance using the formula sum(f(i) * (x(i) - mean)^2)/ [sum(f(i)) - 1], where i = 0 to 6

Standard deviation = square root of variance

value = mean - 1.5 * standard deviation