Answer:
d. t distribution with df = 80
Step-by-step explanation:
Assuming this problem:
Consider independent simple random samples that are taken to test the difference between the means of two populations. The variances of the populations are unknown, but are assumed to be equal. The sample sizes of each population are n1 = 37 and n2 = 45. The appropriate distribution to use is the:
a. t distribution with df = 82.
b. t distribution with df = 81.
c. t distribution with df = 41.
d. t distribution with df = 80
Solution to the problem
When we have two independent samples from two normal distributions with equal variances we are assuming that
And the statistic is given by this formula:
Where t follows a t distribution with
degrees of freedom and the pooled variance
is given by this formula:
This last one is an unbiased estimator of the common variance
So on this case the degrees of freedom are given by:

And the best answer is:
d. t distribution with df = 80
Answer:
18.6 months
Step-by-step explanation:
Given that :
Best fit line from scatterplot :
y=-12.05x +224.26
x = Number of month
y = charge on battery
Number of months a typical battery uses before being dead completely :
When battery is dead completely ; charge =0, y = 0
y = -12.05x + 224.26
0 = - 12.05x + 224.26
12.05x = 224.26
x = 224.26 / 12.05
x = 18.610788
Hence, 18.6 months before battery is completely dead.
Answer: last week he made $630
Step-by-step explanation:
14% of 4500 is 630
The table is proportional and the constant of proportionality is 1.5
Step-by-step explanation:
Proportional relationships are relationships between two variables
where their ratios are equivalent
- One variable is always a constant value times the other
- The relation between the two variables represented graphically by a line passes through the origin point
The table:
→ x : 0 : 2 : 4 : 6
→ y : 0 : 3 : 6 : 9
To prove that y ∝ x find the ratio between each value of y with corresponding value of x
∵ 
∵ 
∵ 
∴ 
∴ k = 1.5
∵ The origin point is in the table
∴ y ∝ x
∴ The table is proportional
The table is proportional and the constant of proportionality is 1.5
Learn more:
You can learn more about proportional in brainly.com/question/10708697
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Given:
A line segment with initial point (–5, 3) and terminal point (1, –6).
To find:
The set of parametric equations over the interval 0 ≤ t ≤ 1 which defines the given line segment.
Solution:
Initial point is (–5, 3). So,

Terminal point is (1, –6).

Check which of the given set of parametric equations satisfy
.
Put t=1 in each set of parametric equations.
In option A,

So, option A is incorrect.
In option B,

So, option B is incorrect.
In option C,


Put t=0, in this set of parametric equations.


So, option C is correct.
In option D,


So, option D is incorrect.