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3 years ago

Can anyone help? Will give Brainly + 20 pts .

Mathematics

1 answer:

katen-ka-za [31]3 years ago

3 0

Answer:

She invested 1600 at 8% (to get the shown $160 interest)

and $7400 at 10% (to get the shown 640 interest)

If x = 4000 then $80 interest is x2 again = $160

and so forth $320 interest x 2 again = $640

Step-by-step explanation:

The format would always be for x and then where

investment - x = interest we can work out totals this way and find x.

9000-x = 800 is first equation and substituted into 2nd equation;

0.10x+0.08(9000−x)=800

Use the distributive property to multiply 0.08 by 9000−x.

0.10x+720−0.08x=800

Combine 0.10x and -0.08x to get 0.02x.

0.02x + 720 = 800

Subtract 720 from both sides.

0.02x=800−720

Subtract 720 from 800 to get 80.

0.02x=80

Divide both sides by 0.02.

x= 80 / 0.02

Make decimals numbers = 1 or above.

80 / 0.02 x 100

x= 8000 / 2

x = 4000

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Read 2 more answers

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

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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 $n = 20$