Given:
Sample size, n = 40
Sample mean, xb = $6.88
Population std. deviation, σ = $1.92 (known)
Confidence interval = 90%
Assume normal distribution for the population.
The confidence interval is
(xb + 1.645*(σ/√n), xb - 1.645*(σ/√n)
= (6.88 + (1.645*1.92)/√40, 6.88 - (1.645*1.92)/√40)
= (7.38, 6.38)
Answer: The 90% confidence interval is (7.38, 6.38)
Answer: -55
Step-by-step explanation: 8/-2 to get -4, then multiply by 4^2 or 16 to get -64, finally add 9 to get -55.
Let 
be the number of liters of the 10% solution to be used, and 
the number of liters of the 4% solution. The chemist wants to end up with a 4 liter solution, so
For each liter used in the mixture, a concentration of either 10% or 4% acid will be contributed, and the goal is to make a 4L solution whose concentration is 7%, which means
Solving for 
gives 
, so 2L of both solutions is needed.
I believe it’s 50% because you divide 8/2 and that’s 4, and 4+8=12
Answer:
Harriet is 16 years of age
Step-by-step explanation:
(x-5)+x=37
2x=42
x=21
21-5=Harriet's Age
