Answer:
(53.812 ; 58.188) ; 156
Step-by-step explanation:
Given that :
Sample size (n) = 51
Mean (m) = 56
Standard deviation (σ) = 9.5
α = 90%
Using the relation :
Confidence interval = mean ± Error
Error = Zcritical * (standard deviation / sqrt (n))
Zcritical at 90% = 1.645
Error = 1.645 * (9.5 / sqrt(51))
Error = 1.645 * 1.3302660
Error = 2.1882877
Hence,
Confidence interval :
Lower boundary = 56 - 2.1882877 = 53.8117123
Upper boundary = 56 + 2.1882877 = 58.1882877
Confidence interval = (53.812 ; 58.188)
2.)
Margin of Error (ME) = 1.25
α = 90%
Sample size = ((Zcritical * σ) / ME)^2
Zcritical at 90% = 1.645
Sample size = ((1.645 * 9.5) / 1.25)^2
Sample size = (15.6275 / 1.25)^2
Sample size = 12.502^2 = 156.3000
Sample size = 156
In B 5^2 = 25. There is no x anywhere.
In C f(x) = 2/x is a function of a reciprocal, not a quadratic.
In D f(x) = 2x^3 + 3x^2 - 5 is a cubic. A cubic is not a quadratic. The highest power of a quadratic is x^2
That leaves A. When you expand the brackets, you get
3(x^2 + 3x- 4x - 12)
2(x^2 - x - 12) when you remove the brackets you get
2x^2 - 2x - 24. The highest power of x is x^2. This is your quadratic.
A<<<< answer.
Answer:
A. $2.25
Step-by-step explanation:
If you subtract $7.50 from $18.75 you get $11.25, then divide that by 5 and you'll get $2.25.
Hope this was useful.
