For margin of error to be a maximum of 3:
3 = z*(SD / sqrt(n)), where z is the z-score, SD is the standard deviation and n is the sample size.
z = 1.96 for a 95% confidence interval, and we are given SD = 15.
3 = 1.96*15/sqrt(n)
sqrt(n) = 9.8
n = 96.04 ~ 96 commercials.
Gas in July is 2.3 times Gas in June
That means Gas in July (252.57) equals 2.3 times gas in June, or “n”
242.57= 2.3 x n and solve for n
Divide both sides by2.3
Calculator gives 105.465
Rounded to nearest HUNDRED is 100
Rounded to nearest HUNDREDTH would be 105.47
Check the answer to see if July gas is 2.3 times June gas
June gas 105.47 x 2.3 is 242.57
So the answer is 105.47 Rounded to nearest hundredth
Step-by-step explanation:
stating the ratios as fractions, setting the two fractions equal to each other, cross-multiplying, and solving the resulting equation