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2 years ago

What is the recursive rule for this geometric sequence? 7, 21, 63, 189,…

Mathematics

1 answer:

Marysya12 [62]2 years ago

4 0

Answer:

The top choice is the answer. a1=7; an= 3*a_(n-1)

Step-by-step explanation:

Begin by finding out what the terms are multiplied by. It is a geometric sequence so multiplication is involved.

Take the 3rd term (63) and divide it by the second term.

63/21 = 3

What this means is that each term in the sequence is multiplied by 3 to get to the next term.

The first term is 7

So the answer is an = 3* a_n-1

The answer must be the top one. See if it works.

a2 = 3*a_(2 -1 )

a2 = 3 * a1

a2 = 3 * 7

a2 = 21 which it does.

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2 years ago

According to national data, 5.1% of burglaries are cleared with arrests. A new detective is assigned to six different burglaries

blagie [28]

Answer:

26.95% probability that at least one of them is cleared with an arrest

Step-by-step explanation:

For each burglary, there are only two possible outcomes. Either it is cleared, or it is not. The probability of a burglary being cleared is independent of other burglaries. 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.

5.1% of burglaries are cleared with arrests.

This means that $p = 0.051$

A new detective is assigned to six different burglaries.

This means that $n = 6$

What is the probability that at least one of them is cleared with an arrest?

Either none are cleared, or at least one is. The sum of the probabilities of these events is 100% = 1. So

$P(X = 0) + P(X \geq 1) = 1$

We want $P(X \geq 1)$

Then

$P(X \geq 1) = 1 - P(X = 0)$

In which

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

$P(X = 0) = C_{6,0}.(0.051)^{0}.(0.949)^{6} = 0.7305$

$P(X \geq 1) = 1 - P(X = 0) = 1 - 0.7305 = 0.2695$

26.95% probability that at least one of them is cleared with an arrest

8 0

2 years ago

Which are the roots of the quadratic function f(b) = 62 – 75? Select two options.

elena55 [62]

Answer:

$b = 5 \sqrt{3} \ or\ b = -5 \sqrt{3}$

Step-by-step explanation:

Given

$f(b) = b^2 - 75$

Required

Determine the roots

To get the root of the function, then f(b) must be 0;

i.e. f(b) = 0

So, the expression becomes

$0 = b^2 - 75$

Add 75 to both sides

$75 + 0 = b^2 - 75 + 75$

$75 = b^2$

Take square roots of both sides

$\sqrt{75} = \sqrt{b^2}$

$\sqrt{75} = b$

Reorder

$b = \sqrt{75}$

Expand 75 as a product of 25 and 3

$b = \sqrt{25*3}$

Split the expression

$b = \sqrt{25} *\sqrt{3}$

$b = \±5 *\sqrt{3}$

$b = \±5 \sqrt{3}$

$b = 5 \sqrt{3} \ or\ b = -5 \sqrt{3}$

The options are not clear enough; however the roots of the equation are $b = 5 \sqrt{3} \ or\ b = -5 \sqrt{3}$

4 0

3 years ago