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MrRa [10]
3 years ago
11

Please help me with this

Mathematics
1 answer:
Sloan [31]3 years ago
7 0

Answer:

The answer is -27.625.

Hope this helps

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due in 5 minutes help! :( All CD’s are on sale for 20% this week. The CD is $9.99. What is the original price of the CD?
bekas [8.4K]

Answer:

$12.49

Step-by-step explanation:

The price right now = 0.8 * the original price

9.99 = 0.8*x

x=12.4875

x≈12.49

Sorry, I thought your problem meant that it was 20% the original price, not 20% off.

6 0
3 years ago
A random sample of 100 people from City A has an average IQ of 120 with a SD of 18. Independently of this, a random sample of 15
Sloan [31]

Answer:

z=\frac{(120-116)-0}{\sqrt{\frac{18^2}{100}+\frac{15^2}{150}}}}=1.837

p_v =P(z>1.837)=1-P(Z  

Comparing the p value with a significance level for example \alpha=0.05 we see that p_v so we can conclude that we have enough evidence to reject the null hypothesis, and we can say that the average IQ on city A is signficantly higher than city B at 5% of singificance.  

Step-by-step explanation:

\bar X_{A}=120 represent the mean for sample 1

\bar X_{B}=116 represent the mean for sample 2

s_{A}=18 represent the sample standard deviation for 1  

s_{B}=15 represent the sample standard deviation for 2  

n_{A}=100 sample size for the group 2  

n_{B}=150 sample size for the group 2  

\alpha Significance level provided

z would represent the statistic (variable of interest)  

Concepts and formulas to use  

We need to conduct a hypothesis in order to check if residents of City A smarter on average, the system of hypothesis would be:  

Null hypothesis:\mu_{A}-\mu_{B}\leq 0  

Alternative hypothesis:\mu_{A} - \mu_{B}> 0  

We don't have the population standard deviation's, but the sample sizes are large enough we can apply a z test to compare means, and the statistic is given by:  

z=\frac{(\bar X_{A}-\bar X_{B})-\Delta}{\sqrt{\frac{s^2_{A}}{n_{A}}+\frac{s^2_{B}}{n_{B}}}} (1)

z-test: Is used to compare group means. Is one of the most common tests and is used to determine whether the means of two groups are equal to each other.

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

z=\frac{(120-116)-0}{\sqrt{\frac{18^2}{100}+\frac{15^2}{150}}}}=1.837

P value

Since is a one right tailed test the p value would be:  

p_v =P(z>1.837)=1-P(Z  

Comparing the p value with a significance level for example \alpha=0.05 we see that p_v so we can conclude that we have enough evidence to reject the null hypothesis, and we can say that the average IQ on city A is signficantly higher than city B at 5% of singificance.  

5 0
3 years ago
I really need help with this problem steps
melamori03 [73]
Solve for y by setting one equation =to X after that you can substitute the equation into the other one let's set the first one in X= FORM
X-7y=10
-2x+14y=-20

Add 7y to both sides of the first equation to let x stand alone
X=7y+10
Now you can substitute x on the second equation
-2 (7y+10)+14y=-20
Distribute
-14y-20+14y=-20
Add and simplify
Us cancel out =0
-20=-20
0=0
They are the same equations you can also divide the second equation by -2 which would make it look like this
X-7y=10
-2 (x-7y=10)
Let me know if I have answered your question
5 0
3 years ago
The price of a stock decreased $2 per day for four consecutive days. What was the total change in value of the stock over the fo
Elena L [17]
It changes by 2 for four days, so it's -$8
6 0
3 years ago
Read 2 more answers
You use 4 gallons of water on 30 plants in your garden. At that rate, how much water will it take to water 45 plants?
Wewaii [24]
Write a proportion like so:

4 gallons/30 plants= x gallons/45 plants

Cross multiply to find the value of x
4*45= 180
180/30= 6=x

Final answer: 6 gallons
4 0
3 years ago
Read 2 more answers
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