A100(1 − α)% confidence interval for the mean μ of a normal population when the value of σ is known is given byleftparen1.gifx − zα/2 ·σsqrt1a. gif n, x + zα/2 ·σsqrt1a. gif nrightparen1.gif. by how much must the sample size n be increased if the width of the ci above is to be halved? halving the length requires n to be increased by a factor of .if the sample size is increased by a factor of 49, what effect will this have on the width of the interval?

Ok here we go ..there are plenty of ways to solve such math problems but we will go for the smartest and easiest ..5x+2y=7  -2x+6y=9we rearrange them into the following ..by multiplying the 1st equation by 2 it becomes 10x + 4y = 14we rearrange it and so it becomes 10x = 14 - 4yas for the second equation we multiply it by 5 and rearrange it so it becomes as to the following ..-10x + 30y = 45rearranging so 10x = 30y -45now 10x equals both 14 - 4y and 30y -45so   14 - 4y = 30y -4531 = 26yy= 31/26 = 1.19 or around 1.2so by now we can calculate x easily as  -2x+6y=9so 2x = 6y -9 = 6 * 31/26 - 9 = -1.84  then x = - 0.92 or around -0.9best luck!