Option B: is the value of y
Explanation:
It is given that "Two times x is 8 more than y". Writing it as expression, we have,
It is also given that "The sum of x and two times y is 14". Writing it as expression, we have,
To find the value of y, let us solve the two equations using substitution method.
From the equation , let us find the value of x.
Now, substituting in the equation
, we get,
Thus, the value of y is
Answer:
a) To determine the minimum sample size we need to use the formula shown in the picture 1.
E is the margin of error, which is the distance from the limits to the middle (the mean) of the confidence interval. This means that we have to divide the range of the interval by 2 to find this distance.
E = 0.5/2 = 0.25
Now we apply the formula
n = (1.645*0.80/0.25)^2 = 27.7 = 28
The minimum sample size would be 28.
b) To answer the question we are going to make a 90% confidence interval. The formula is:
(μ - E, μ + E)
μ is the mean which is 127. The formula for E is shown in the picture.
E = 0.80*1.645/√8 = 0.47
(126.5, 127.5)
This means that the true mean is going to be contained in this interval 90% of the time. This is why it doesn't seem possible that the population mean is exactly 128.
