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Answer:
We reject the null hypothesis and accept the alternate hypothesis. Thus, it be concluded that the population mean is less than 20.
Step-by-step explanation:
We are given the following in the question:
Population mean, μ = 60
Sample mean, = 19.5
Sample size, n = 60
Alpha, α = 0.05
Population standard deviation, σ = 1.8
First, we design the null and the alternate hypothesis
We use One-tailed z test to perform this hypothesis.
Formula:
Putting all the values, we have
Now,
Since,
We reject the null hypothesis and accept the alternate hypothesis. Thus, it be concluded that the population mean is less than 20.
<u>Answer</u>
Graph D represents the national debt of the country over the next years.
<u>Solution-</u>
The country's debt will decrease exponentially by one-third each year.
Current debt is $60 billion.
This problem can be treated as an exponential decay problem.
The general exponential decay function is,
Where,
a = initial value,
r = rate of change,
-ve sign of x represents the decrease in value of y as x increases.
Here, the rate of change is 3 as each year the debt becomes on third, and initial value of debt is $60, so
Plotting a graph taking number of year on x-axis and debt on y-axis, we can generate a graph for this function.
Putting different values of x, we can get the values of y. So the graph must have (0, 60), (1, 20), (2, 6.66), (3, 2.22), (4, 0.74), (5, 0.24) points on it.
Option B and C are incorrect, as they do not start from 60. (they don't have (0,60) on their curve)
Between option A and D, curve in D has all the points on it. So D is the correct graph.
