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3 years ago

Double the difference of a number n and 3 is -10. Which equation models this "number riddle" correctly?

Mathematics

1 answer:

Cerrena [4.2K]3 years ago

7 0

Answer: D

Explanation

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Luisa recieved $108 for a necklace she sold on an online auction. The auction site took a fe of 10% of selling price. What was t

Vera_Pavlovna [14]

I believe it might be 107.9 after if that’s what your asking-like taking off 10% of $108.

3 0

2 years ago

The population standard deviation for the temperature of beers found in Scooter's Tavern is 0.26 degrees. If we want to be 90% c

siniylev [52]

Answer:

19 beers must be sampled.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1 - 0.9}{2} = 0.05$

Now, we have to find z in the Z-table as such z has a p-value of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.05 = 0.95$ , so Z = 1.645.

Now, find the margin of error M as such

$M = z\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

The population standard deviation for the temperature of beers found in Scooter's Tavern is 0.26 degrees.

This means that $\sigma = 0.26$

If we want to be 90% confident that the sample mean beer temperature is within 0.1 degrees of the true mean temperature, how many beers must we sample?

This is n for which M = 0.1. So

$M = z\frac{\sigma}{\sqrt{n}}$

$0.1 = 1.645\frac{0.26}{\sqrt{n}}$

$0.1\sqrt{n} = 1.645*0.26$

$\sqrt{n} = \frac{1.645*0.26}{0.1}$

$(\sqrt{n})^2 = (\frac{1.645*0.26}{0.1})^2$

$n = 18.3$

Rounding up:

19 beers must be sampled.

7 0

2 years ago

Kim is x years old. Jordan is 9 years older than Kim. Five times Jordan’s age is equal to 110.

soldi70 [24.7K]

J=9+x

5J=110

A) 110=5(9+x)

110=45+5x

65=5x

13=x

B) Kim is 13 years old

J=9+x

J=9+13

J=22

C) Jordan is 22 years old

6 0

3 years ago

What is 15×70?????????

I am Lyosha [343]

Fifthteen(15)xseventy (70)= 1,050

6 0

3 years ago

Read 2 more answers

Solving Exponential Equations (lacking a common base)<br> 31^d=38

Bond [772]

Answer:

d = log 38/log31

d = 1.06

Step-by-step explanation:

31 ^ d = 38

Take log of both sides since the exponential equation have different base (always)

d log 31 = log 38

d = log 38 / log 31

d = 1.58 / 1.491

d = 1.06.

We can actually check to see if this is correct.

Substituting d = 1.06

31^ 1.06 = 38.092

(You see, that's approximately correct)

Keep learning, maths is fun!

8 0

3 years ago