Step-by-step explanation:
5x=11-7
5X= 4
X=4/5
=0.8 Answer
- 84.7 + 59.2, this is your expression
We cannot calculate the confidence interval without the sample size. However, for the second question, the sample size needed would be 49.
The formula we use is

To find the z-score:
Convert 98% to a decimal: 0.98
Subtract from 1: 1-0.98 = 0.02
Divide by 2: 0.02/2 = 0.01
Subtract from 1: 1-0.01 = 0.99
Using a z-table (http://www.z-table.com) we see that this value is closest to a z-score of 2.33.
Using the z-score, our standard deviation (9) and our margin of error (3), we have:
Note that h(x) = 4x^2 - 8x - 60 factors to 4(x^2 - 2x - 15), and that the roots (zeros) of (x^2 - 2x - 15) are -5 and +3. Thus, the smallest zero is -5.