Answer:
1877 computer users
Step-by-step explanation:
We have that for 95% of confident, the value of z has a value of 1.96 (attached table about it), they also mention the margin of error (E) that is 10 and finally the standard deviation (sd) that has a value of 221.
We apply the following formula:
n = [z * sd / E] ^ 2
replacing:
n = [1.96 * 221/10] ^ 2
n = 1876.27
that is, the minimum sample size is 1877
6 x 7 = 42
And the missing number is 8, because 7 x 8 = 56.
If you mean that you want to solve the equation for v, then all you need to do is to multiply both sides by 3:
