N = 20, r = 15;
n C r = ( n * ( n - 1) ( n - 2 ) ... ( n - r + 1 )) / r ! =
20 C 15 = (20 * 19 * 18 * 17 ......8 * 7 * 6) / (15 * 14 * 13 ...* 5 * 4 * 3 * 2 * 1) =
= 15,504
Answer:
They can choose 15 questions in 15,504 ways.
Answer:
45
Step-by-step explanation:
Answer:
a) 
b) Null hypothesis: 
Alternative hypothesis: 
And we can use a t test procedure in order to check if the true mean is equat to the desired value.
Step-by-step explanation:
For this case we know that this:
Claim: The mean pulse rate (in beats per minute) of adult males is equal to 69.5 bpm
Part a
If we convert this with symbols we can write this as:

Part b
We have the following info given:
represent the sample mean
represent the sample size
We have the following system of hypothesis:
Null hypothesis: 
Alternative hypothesis: 
And we can use a t test procedure in order to check if the true mean is equat to the desired value.
Answer:

Step-by-step explanation:
In this cross sections problem, we can integrate from -r to +r (so that the integral covers the entire base of the solid).

The formatting for the integral did not let me put -r on the lower bound, so i replaced it with a, just know that a represents -r here.
Evaluating the integral gives use that it is equal to;

Caution: this answer may not meet your needs, but this is the answer I have come up with with the given information.
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Answer:
m∠B =
.
Step-by-step explanation:
Since the three sides of the triangle are given, then we apply cosine rule.
=
+
- 2ac Cos B
But, a = 660 cm, b = 680 cm, and c = 100 cm.
So that;
=
+
-2(660 x 100) Cos B
462400 = 435600 + 10000 - 132000 Cos B
462400 = 445600 - 132000 Cos B
132000 Cos B = 445600 - 462400
= -16800
Cos B = 
= -0.1273
B =
-0.1273
= 
Thus, measure of ∠B is
.