First, find the mean. You'll need it to compute the variance.

The variance of the sample is then computed with the formula

The standard deviation is the square root of the variance, so
Answer:
Ava is 10 years old
Step-by-step explanation:
Sara is 8
Sara=$8 per week for 12 weeks
$8×12 weeks=$96
Ava has $24 more than Sara
x*12=96$+$24
12x=120
x=120/12
x=10
Ava's age is 10
3x^2 + 6x - 10 = 0
3(x^2 + 2x) - 10 = 0
3[ (x + 1)^2 - 1 ] - 10 = 0
3(x+1)^2 - 13 = 0
so the vertex is at (-1,-13)
the roots will be same distance from x = -1
that is a distance 1.08 --1 = 2.08
so other root is approximately -1 -2.08 = -3.08
the other intercept is at (-3.08,0)
Travel distance by light in a second = 3*10^5 kms
Travel distance by light in 60 seconds =
3*10^5 * 60
180 * 10^5
1.8 * 10^7 kms