Find the indicated area under the curve of the standard normal distribution; then convert it to a percentage and fill in the blank.
about [ans1] % of the area is between z = −1 and z = 1 (or within 1 standard deviation of the mean).

80

step-by-step explanation:

step-by-step explanation:

the ratio of red paint to blue paint is always 9/7. that means that, whatever x's value, (4x+12)/(4x-4) has that same ratio. so, set up an equation and cross-multiply to solve for x:

9/7 = (4x+12)/(4x-4)

9(4x-4) = 7(4x+12)

36x - 36 = 28x + 84

8x - 36 = 84

8x = 120

x = 15