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2 years ago

13

Tessa had $90 in her checking account. She paid her cable/internet bill for $60. She deposited $50 from her part-time job before

writing a check for $65 to pay her credit card bill. What is Tessa's account balance?

2 answers:

LenKa [72]2 years ago

6 0

The answer is $15 in her account

Lady bird [3.3K]2 years ago

4 0

90-60+50-65=15

$15 in her account

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jill mixes two types of concentrations od hci (hydrochloric acid) 0.375 liters of 25% hydrochloric acid and 0.625 liters of 65%

Sonja [21]

Answer:

The concentration of HCl in the mixture is 1L of 50% HCl

Step-by-step explanation:

Here, we want to know the percentage of HCl present which refers to the its concentration.

Firstly, the total volume we have is 0.375 + 0.625 = 1 L

we can calculate the percentage as follows;

The percentage of the 25% present is 37.5%

while the percentage of the 75% present is 62.5%

When we say the percentage present, we are referring to the amounts of the total liters which is 1 present.

So the concentration of the final mixture will be;

(37.5% of 25) + (62.5% of 65)

= 9.375% + 40.625%

Adding both gives = 50%

So the concentration we have is 1L of 50% HCl

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2 years ago

If 400 mL of a 20% w/v solution were diluted to 2 L, what would be the final percentage strength?

irakobra [83]

Answer:

4%

Step-by-step explanation:

A 20% solution with a total volume of 400 mL has 20% * 400 mL of solute.

20% * 400 mL = 80 mL

When you dilute the solution to 2 L, you introduce additional water, but no additional solute, so now you have the same 80 mL of solute in 2 L of total solution.

The concentration is:

(80 mL)/(2 L) = (80 mL)/(2000 mL) = 0.04

As a percent it is:

0.04 * 100% = 4%

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2 years ago

Alice purchased 4 1⁄2 kilograms of olive oil for $27. What is the price per kilogram?

vitfil [10]

Hi!

We will solve this using ratios, like this:

4 1/2 = 4,5 kg of olive oil for 27 $

1 kg of olive oil for x $

_____________________________

x = (27*1)/4,5

x = 27/4,5

x = 6 $ per kilogram

Hope this helps!

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2 years ago

The 99 percent confidence interval for the average weight of a product is from 71.36 lbs. to 78.64 lbs. Can we conclude that μ i

Ilya [14]

Answer:

Step-by-step explanation:

Hello!

To decide over a hypothesis test using a confidence interval the following conditions are to be met:

1. The hypotheses should be two-tailed.

2. The hypotheses and the confidence interval should be made for the same parameter.

3. The confidence level and the significance level should be complementary, so if the CI is 1-α: 0.99 the level of significance should be α: 0.01

If all conditions are met, the decision rule is the following:

If the value stated in the null hypothesis is contained by the CI, the decision is to not reject the null hypothesis.

If the value stated in the null hypothesis is not contained by the CI, the decision is to reject the null hypothesis.

Let's say in this example the hypotheses are:

H₀: μ = 71

H₁: μ ≠ 71

α: 0.01

99% Confidence level is (71.36;78.64).

As you can see, 71 is not contained in the CI so the decision to take is to reject the null hypothesis, in other words, the population mean is not 71.

I hope it helps!

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2 years ago

In choice situations of this type, subjects often exhibit the "center stage effect," which is a tendency to choose the item in t

victus00 [196]

Complete Question

The complete question is shown on the first uploaded image

Answer:

a

The probability that he or she would choose the pair of socks in the center position is $p =\frac{1}{5}$

The correct answer choice is

X has a binomial distribution with parameters n=100 and p=1/5

b

The mean is $\mu = 20$

The standard deviation is $\sigma=4$

c

The probability, $P =0.0002$

d

The correct answer is

The experiment supports the center stage effect. If participants were truly picking the socks at random, it would be highly unlikely for 34 or more to choose the center pair.

Using the R the probability $Pe = 0.0003$

The probabilities $P \approx Pe$

Step-by-step explanation:

Since the person selects his or her desired pair of socks at random , then the probability that the person would choose the pair of socks in the center position from all the five identical pair is mathematically evaluated as

$p =\frac{1}{5}$

$=0.2$

The mean of this distribution is mathematical represented as

$\mu = np$

substituting the value

$\mu = 100 * 0.2$

$\mu = 20$

The standard deviation is mathematically represented as

$\sigma = \sqrt{np (1-p)}$

substituting the value

$= \sqrt{100 * 0,2 (1-0.2)}$

$\sigma=4$

Applying normal approximation the probability that 34 or more subjects would choose the item in the center if each subject were selecting his or her preferred pair of socks at random would be mathematically represented as

$P=P(X \ge 34 )$

By standardizing the normal approximation we have that

$P(X \ge 34) \approx P(Z \ge z)$

Now z is mathematically evaluated as

$z = \frac{x-\mu}{\sigma }$

Substituting values

$z = \frac{34-20}{4}$

$=3.5$

So using the z table the $P(Z \ge 3.5)$ is 0.0002

The probability P and Pe that 34 or more subject would choose the center pair is very small So

The correct answer is

The experiment supports the center stage effect. If participants were truly picking the socks at random, it would be highly unlikely for 34 or more to choose the center pair.

6 0

2 years ago