Goran is participating in a 6-day cross-country biking challenge. He biked for 51, 65, 62, 46, and 62 miles on the first five

A culture started with 5,000 bacteria. After 4

Tresset [83]

Answer: After 13 (12) hours, there would be 6,500 bacteria across the culture.

Step-by-step explanation:

The bacteria grew by 500 each 4 hours, so to know how much there would be 13 hours later:

Simple, add 500 bacteria to every 4 hours until you reach 13 hours. 4 = 5.5k, 8 = 6k, 12 = 6.5k. Now, 12 is closer to 13 than anything we would've gotten if we kept going.

And there's your answer.

7 0

2 years ago

Sold 685 boxes of cookies about how many boxes are they sold rounded to the nearest ten

MissTica

Answer:

690

Step-by-step explanation:

Round from the tens place.

8 0

3 years ago

If 112 people attend a concert and tickets for adults cost $2.25 while tickets for children cost $and total receipts for the con

Brut [27]

Answer:

42 child and 70 adult

Step-by-step explanation:

Let a = number of adult tickets

c = number of child tickets

a+c = 112

2.25a + 1.75c = 231

Solve the first equation for a

a = 112-c

Substitute this into the second equation

2.25(112-c) + 1.75c = 231

Distribute

252 - 2.25c +1.75c = 231

Combine like terms

252 -.5c = 231

Subtract 252 from each side

252-252 -.5c = 231-252

-.5c = -21

Divide each side by -.5

-.5c/-.5 = -21/ -.5

c = 42

Now can find a

a = 112-c

a = 112-42

a = 70

4 0

3 years ago

Read 2 more answers

A study was conducted to measure the effectiveness of hypnotism in reducing pain. The measurements are centimeters on a pain sca

saul85 [17]

Answer:

The 95% confidence interval for the difference would be given by (-1.776;0.376)

We are 95% confidence that the true mean difference is between $-1.776 \leq \mu_d \leq 0.376$ . Since the confidence interval contains the value 0, we don't have enough evidence to conclude that hypnotism appear to be effective in reducing pain.

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

Let put some notation

x=test value before , y = test value after

x: 6.4 2.6 7.7 10.5 11.7 5.8 4.3 2.8

y: 6.7 2.4 7.4 8.1 8.6 6.4 3.9 2.7

The differences defined as $d_i = y_i -x_i$ and we got:

d: 0.3, -0.2, -0.3, -2.4, -3.1, 0.6, -0.4, -0.1

We can calculate the mean and the deviation for the sample with the following formulas:

$\bar d=\frac{\sum_{i=1}^n d_i}{n}$

$s_d =\frac{\sum_{i=1}^n (d_i -\bar d)^2}{n-1}$

$\bar d=-0.7$ represent the sample mean for the difference

$\mu_d$ population mean (variable of interest)

$s_d$ =1.32 represent the sample standard deviation

n=8 represent the sample size

Confidence interval

The confidence interval for the mean is given by the following formula:

$\bar d \pm t_{\alpha/2} *\frac{s_d}{\sqrt{n}}$ (1)

In order to calculate the critical value t we need to find first the degrees of freedom, given by:

$df=n-1=8-1=7$

Since the Confidence is 0.95 or 95%, the value of alpha=0.05 and \alpha/2 =0.025, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,8)".And we see that $t_(\alpha/2)=2.306$

Now we have everything in order to replace into formula (1):

$-0.7-2.306\frac{1.32}{\sqrt{8}}=-1.776$

$-0.7+2.306\frac{1.32}{\sqrt{8}}=0.376$

So on this case the 95% confidence interval for the difference would be given by (-1.776;0.376)

We are 95% confidence that the true mean difference is between $-1.776 \leq \mu_d \leq 0.376$ . Since the confidence interval contains the value 0, we don't have enough evidence to conclude that hypnotism appear to be effective in reducing pain.

6 0

3 years ago

In February, Alec had 1,586 visitors to his website. In March, he had 1,352 visitors to his website. What is the percentage decr

Deffense [45]

Answer:

The percentage decrease of the number of visitors to Alec's website from February to March is 14.8 %

Step-by-step explanation:

Explanation:

Percent decrease is a measure of percent change, which is the extent to which something loses value.

Step 1:

Find out the difference (decrease) between the number of visitors in march and February

Decrease =number of visitors in Fe bury- Number of vsitors in march

Decrease= 1,586- 1,352

Decrease =234

Step 2:

Divide the decrease by the original number of visitors and multiply the answer by 100.

Percent decrease= $\frac{Decrease }{ Original Number }\times100$

Percent decrease= $\frac{236}{1586}\times100$

Percent decrease= $0.148\times100$

Percent decrease =14.88

8 0

3 years ago