5/8 - 3/10
Find the common denominator:
Multiples of 8: 8, 16, 24, 32, 40 (8 x 5 = 40)
Multiples of 10: 10, 20, 30, 40 (10 x 4 = 40)
5/8 = 5*5 / 8*5 = 25/40
3/10 = 3*4 / 10 *4 = 12/40
Now you have 25/40 - 12/40
25 -12 = 13
Answer = 13/40
The answer is A.
According to the empirical rule, roughly 68% of the scores fall between z = -1 and z = 1
You can use a calculator to get a more approximate answer. If you have a TI calculator, you can use the "normalcdf" function to type in normalcdf(-1,1)
