Due tomorrow! 20
solve all
find x and y
system of linear equations

1. 2x - 3y = 4
-2x + 3y = -10

2. -2x + 5y = 6
2x - 5y = -6

3. -3x + 4y = 3
-12x + 16 = 8

4. 6x + y = -1
-6x - 4y = 4

Arandom sample of n = 25 observations is taken from a n(µ, σ ) population. a 95% confidence interval for µ was calculated to be (42.16, 57.84). the researcher feels that this interval is too wide. you want to reduce the interval to a width at most 12 units. a) for a confidence level of 95%, calculate the smallest sample size needed. b) for a sample size fixed at n = 25, calculate the largest confidence level 100(1 − α)% needed.