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irinina [24]
3 years ago
5

I need help with this please

Mathematics
1 answer:
Vitek1552 [10]3 years ago
7 0
The answer to 8a. is 17, the answer to 8b. is 3.9, the answer to 8c. is 1 / 2, the answer to 8d. is 7 7 / 8, the answer to 9a. is commutative property, the answer to 9b. is multiplicative identity property, the answer to 9c. is associative property, and the answer to 9d. is additive inverse property.

Regarding the whole "explain using mental math" thing, I pretty much just used the fact that 8a. and 8b. both had the same number of decimal places. For 8c., I just made each number have a denominator of 10. And last, for 8d., all of the denominators were already the same, which made it pretty easy. I apologize for this section of my answer being so informal lol, I haven't had to do these kinds of problems in like 5 years <span />
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If Mary walks 3 feet every 2 seconds, how many feet does she walk in an hour?
lara31 [8.8K]
There are 30, 2 seconds in an hour. So you multiply the feet by 30 to get 90 feet.
6 0
4 years ago
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Jessica has $35.She gives 2/5 oh her money to her sister.How much money did she give her sister?
omeli [17]
She gave $14 to her sister.

Explanation:
The word "of" in fraction word problems USUALLY signals for you to multiply. So, we want to find 2/5 of 35, so we multiply 2/5 x 35. That gives us 14, therefore she gave $14 to her sister
6 0
3 years ago
An automobile manufacturer claims that its van has a 31.3 miles/gallon (MPG) rating. An independent testing firm has been contra
Yuliya22 [10]

Answer:

z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}} (1)  

z=\frac{31.1-31.3}{\frac{1.3}{\sqrt{140}}}=-1.82  

p_v =2*P(z  

If we compare the p value and the significance level given \alpha=0.02 we see that p_v>\alpha so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, so we can conclude that the true mean is NOT significantly different from 31.3 at 2% of signficance.  

Step-by-step explanation:

Data given and notation  

\bar X=31.1 represent the sample mean

\sigma=1.3 represent the population standard deviation for the sample  

n=140 sample size  

\mu_o =31.3 represent the value that we want to test  

\alpha=0.02 represent the significance level for the hypothesis test.  

z would represent the statistic (variable of interest)  

p_v represent the p value for the test (variable of interest)  

State the null and alternative hypotheses.  

We can assume that we conduct a hypothesis in order to check if the true mean is equal to 31.3 , the system of hypothesis would be:  

Null hypothesis:\mu =31.3  

Alternative hypothesis:\mu \neq 31.3  

Since we know the population deviation, is better apply a z test to compare the actual mean to the reference value, and the statistic is given by:  

z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}} (1)  

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".  

Calculate the statistic  

We can replace in formula (1) the info given like this:  

z=\frac{31.1-31.3}{\frac{1.3}{\sqrt{140}}}=-1.82  

P-value  

Since is a two-sided test the p value would be:  

p_v =2*P(z  

Conclusion  

If we compare the p value and the significance level given \alpha=0.02 we see that p_v>\alpha so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, so we can conclude that the true mean is NOT significantly different from 31.3 at 2% of signficance.  

5 0
3 years ago
What is the weight In grams of a liquid that exactly fills a 203.0 ml container if the density of the liquid is 0.685?
Serhud [2]

Answer:

the weight of a liquid is 138.37 grams.

Step-by-step explanation:

we are given that the volume of the container=202 ml(milliliter).

also, the density of the liquid is given =0.685 grams over milliliter.

we know that the mass or weight of the liquid is given by:

weight=density×volume .

weight=(0.685×202) grams.

weight=138.37 grams.

hence, the weight of the liquid that exactly fills a 202.0-milliliter container is 138.37 grams.

7 0
3 years ago
Write 2 ratios that are equivalent to 9/12
zhenek [66]
Two ratios are 3:4 and 18:24
7 0
3 years ago
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