Geometry Question Find the area of the circle
2 answers:
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Answer:
Correct choice is B
Step-by-step explanation:
Let a, b, c and d be the trapezoid's sides lengths.
The perimeter of the trapezoid is the sum of all sides lengths, thus,
If each side length is increased by a factor 7, then new sides have lengths 7a, 7b, 7c and 7d. The perimeter of new trapezoid is
Use the distributive property for this expression:
Since then
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:
5091 Km/hr and 505 km/hr
Step-by-step explanation:
Speed = Distance / Time
Let the speed of first automobile be 'x' and that of the second be 'y'
Since speed of one is 10 times greater than the other. therefore;
⇒ x = 10 y
also let time for faster automobile be 'T' and time for slower auto mobile be 't'
Since first arrive one hour earlier than second, therefore;
⇒ t = T + 1
⇒ For first automobile; ; substituting for 'x' and 'T'. Therefore;
⇒
⇒ For Second automobile;
⇒
⇒
⇒ 5600 + = 560
⇒ 5600 - 560 = -
⇒ t = 1.11 hr
also ; T = 1.11 - 1 = 0.11 hr
Speed of 1st auto = 560/0.11 = 5091 km /hr
Speed of 2nd auto = 560/1.11 = 505 km/hr