Answer: 4,000
Step-by-step explanation:
It is in the thousands place
Answer:
![\mu = 20.3](https://tex.z-dn.net/?f=%20%5Cmu%20%3D%2020.3)
![\sigma = 4.9](https://tex.z-dn.net/?f=%5Csigma%20%3D%204.9)
And we can find the limits in order to consider values as significantly low and high like this:
![Low\leq \mu -2 \sigma= 20.3- 2*4.9 = 10.5](https://tex.z-dn.net/?f=%20Low%5Cleq%20%5Cmu%20-2%20%5Csigma%3D%2020.3-%202%2A4.9%20%3D%2010.5)
![High\geq \mu +2 \sigma= 20.3+ 2*4.9 = 30.1](https://tex.z-dn.net/?f=%20High%5Cgeq%20%5Cmu%20%2B2%20%5Csigma%3D%2020.3%2B%202%2A4.9%20%3D%2030.1)
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".
Solution to the problem
For this case we can consider a value to be significantly low if we have that the z score is lower or equal to - 2 and we can consider a value to be significantly high if its z score is higher tor equal to 2.
For this case we have the mean and the deviation given:
![\mu = 20.3](https://tex.z-dn.net/?f=%20%5Cmu%20%3D%2020.3)
![\sigma = 4.9](https://tex.z-dn.net/?f=%5Csigma%20%3D%204.9)
And we can find the limits in order to consider values as significantly low and high like this:
![Low \leq \mu -2 \sigma= 20.3- 2*4.9 = 10.5](https://tex.z-dn.net/?f=%20Low%20%5Cleq%20%5Cmu%20-2%20%5Csigma%3D%2020.3-%202%2A4.9%20%3D%2010.5)
![High\geq \mu +2 \sigma= 20.3+ 2*4.9 = 30.1](https://tex.z-dn.net/?f=%20High%5Cgeq%20%5Cmu%20%2B2%20%5Csigma%3D%2020.3%2B%202%2A4.9%20%3D%2030.1)
You can use a tangent:
![tangent=\dfrac{opposite}{adjacent}](https://tex.z-dn.net/?f=tangent%3D%5Cdfrac%7Bopposite%7D%7Badjacent%7D)
We have opposite = 17 and adjacent = x.
![\tan30^o=\dfrac{\sqrt3}{3}](https://tex.z-dn.net/?f=%5Ctan30%5Eo%3D%5Cdfrac%7B%5Csqrt3%7D%7B3%7D)
substitute:
cross multiply
multiply both sides by √3
![x(\sqrt3)(\sqrt3)=51\sqrt3](https://tex.z-dn.net/?f=x%28%5Csqrt3%29%28%5Csqrt3%29%3D51%5Csqrt3)
divide both sides by 3
![x=17\sqrt3](https://tex.z-dn.net/?f=x%3D17%5Csqrt3)
Use the Pythagorean theorem:
![y^2=(17\sqrt3)^2+17^2\\\\y^2=289(\sqrt3)^2+289\\\\y^2=289\cdot3+289\\\\y^2=867+289\\\\y^2=1156\to y=\sqrt{1156}\\\\y=34](https://tex.z-dn.net/?f=y%5E2%3D%2817%5Csqrt3%29%5E2%2B17%5E2%5C%5C%5C%5Cy%5E2%3D289%28%5Csqrt3%29%5E2%2B289%5C%5C%5C%5Cy%5E2%3D289%5Ccdot3%2B289%5C%5C%5C%5Cy%5E2%3D867%2B289%5C%5C%5C%5Cy%5E2%3D1156%5Cto%20y%3D%5Csqrt%7B1156%7D%5C%5C%5C%5Cy%3D34)
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Other method.
triangle.
The sides are in the ratio ![1:2:\sqrt3\to17:y:x](https://tex.z-dn.net/?f=1%3A2%3A%5Csqrt3%5Cto17%3Ay%3Ax)
Therefore
![17:(2\cdot17):(17\sqrt3)\to17:34:17\sqrt3\to x=34,\ y=17\sqrt3](https://tex.z-dn.net/?f=17%3A%282%5Ccdot17%29%3A%2817%5Csqrt3%29%5Cto17%3A34%3A17%5Csqrt3%5Cto%20x%3D34%2C%5C%20y%3D17%5Csqrt3)
You first have to convert the 5 tons to pounds.
Once you have done that step you simply add.
We are told to use simple interest rate. Formula for this is:
![A=P*(1+r*t)](https://tex.z-dn.net/?f=A%3DP%2A%281%2Br%2At%29)
Where:
A= total accumulated amount (principal + interest)
P= principal
r= yearly percentage rate
t= number of years
We need to save $19500 for the first year at a college. This is the amount we will have at the account after five years. In our case this is A.
Principal is the amount we need to put into savings to get the total amount needed. In our case this is P.
Yearly percentage rate is the percentage by which our savings increase at the end of a year. In our case this is r.
t is number of years that we are holding our money on the bank account.
To solve this problem we will assume that we are putting same amount each month on the bank account.
We are given:
A=$19500
P=?
r=1.5%
t=5 years
First step is to transform r into decimal number:
![r= \frac{1.5}{100} =0.015](https://tex.z-dn.net/?f=r%3D%20%5Cfrac%7B1.5%7D%7B100%7D%20%3D0.015)
Now we get back to our formula and we solve it for P:
![A=P*(1+r*t) \\ P= \frac{A}{1+r*t}](https://tex.z-dn.net/?f=A%3DP%2A%281%2Br%2At%29%20%5C%5C%20P%3D%20%5Cfrac%7BA%7D%7B1%2Br%2At%7D%20)
We insert numbers and we get our principal:
![P= \frac{19500}{1+0.015*5} \\ P=18139.53](https://tex.z-dn.net/?f=P%3D%20%5Cfrac%7B19500%7D%7B1%2B0.015%2A5%7D%20%20%5C%5C%20P%3D18139.53)
We need to put $18139.53 into savings to get required amount after 5 years or 5*12=60months. Assuming that we put same amount each month into savings we need to put
![18139.53 / 60 = 302.33](https://tex.z-dn.net/?f=18139.53%20%2F%2060%20%3D%20302.33)
This is our solution for this problem. This is closest to the amount we would need to put in real life. In real life we would earn interest onto interest and our monthly amount would be smaller.