There is a way to work it out with a pencil and paper, but that's too complicated
to try and explain with only text, like we have here.
I don't usually recommend this for things that can be done easily on paper ...
but for square roots, your best bet is to use a calculator.
The square root of 30 does not come out even. It starts out 5.477225...
and it keeps going and never ends.
The negative of 5.477225... is also a square root of 30. Every number has
two square roots ... the positive and negative of the same number.
Answer:
(115.2642, 222.7358).
Step-by-step explanation:
Given data:
type A: n_1=60, xbar_1=1827, s_1=168
type B: n_2=180, xbar_2=1658, s_2=225
n_1 = sample size 1, n_2= sample size 2
xbar_1, xbar_2 are mean life of sample 1 and 2 respectively. Similarly, s_1 and s_2 are standard deviation of 1,2.
a=0.05, |Z(0.025)|=1.96 (from the standard normal table)
So 95% CI is
(xbar_1 -xbar_2) ± Z×√[s1^2/n1 + s2^2/n2]
=(1827-1658) ± 1.96×sqrt(168^2/60 + 225^2/180)
= (115.2642, 222.7358).
Answer:
Step-by-step explanation:
