A regular polygon has 15 sides. Which is a possible angle of rotational symmetry for the figure? 12° 45° 72° 90°

Mathematics

2 answers:

iren2701 [21]2 years ago

7 0

Answer:

Option (3). 72°

Step-by-step explanation:

Angle of rotational symmetry = Central angle of a polygon

That means when we rotate the regular polygon by a central angle, polygon overlaps itself.

Central angle of a polygon with n sides = $\frac{360}{n}$

Where n = number of sides of the polygon

Therefore, central angle of a polygon with 15 sides = $\frac{360}{15}$

= 24°

Central angle tells us that after every 24° of rotation, polygon overlaps itself.

Angle of rotational symmetry may be 48°, 72°, 96°.....

Therefore, Option (3) is the possible angle of rotational symmetry.

Luda [366]2 years ago

5 0

Answer:

Step-by-step explanation:

took the test and 72 was correct

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The probability that your call to a service line is answered in less than 30 seconds is 0.75. Assume that your calls are indepen

vfiekz [6]

Answer:

a) 0.2581

b) 0.4148

c) 17

Step-by-step explanation:

For each call, there are only two possible outcomes. Either they are answered in less than 30 seconds. Or they are not. The probabilities for each call are independent. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

In which $C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

And p is the probability of X happening.

In this problem we have that:

$p = 0.75$

a. If you call 12 times, what is the probability that exactly 9 of your calls are answered within 30 seconds? Round your answer to four decimal places (e.g. 98.7654).

This is $P(X = 9)$ when $n = 12$ . So

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 9) = C_{12,9}.(0.75)^{9}.(0.25)^{3} = 0.2581$

b. If you call 20 times, what is the probability that at least 16 calls are answered in less than 30 seconds? Round your answer to four decimal places (e.g. 98.7654).

This is $P(X \geq 16)$ when $n = 20$