A. The point estimate of μ1 − μ2 is calculated using the value of x1 - x2, therefore:
μ1 − μ2 = x1 – x2 =
7.82 – 5.99
μ1 − μ2 = 1.83
B. The formula for
confidence interval is given as:
Confidence interval
= (x1 –x2) ± z σ
where z is a value
taken from the standard distribution tables at 99% confidence interval, z =
2.58
and σ is calculated
using the formula:
σ = sqrt [(σ1^2 /
n1) + (σ2^2 / n2)]
σ = sqrt [(2.35^2 /
18) + (3.17^2 / 15)]
σ = 0.988297
Going back to the
confidence interval:
Confidence interval
= 1.83 ± (2.58) (0.988297)
Confidence interval
= 1.83 ± 2.55
Confidence interval
= -0.72, 4.38
It is true that (x+2)(x+3) = x2 +5x + 6
<span>y^2 + 5y + 6
=</span><span>(y + 2)(y + 3)
----------------------------------</span>
X= my age
500-3x=230
500-3x-230=230-230
270-3x=0
270-3x+3x=0+3x
270=3x
270/3=3x/3
x=90
you are 90 years old
