Answer:
The age of the person who entered the room is 15
Step-by-step explanation:
We are given:
Ages of 5 people in a room are:
17, 16, 15, 17, 22
A person enters room, and then the mean age of 6 people is 17.
We need to find the age of person who entered the room.
The formula to calculate mean is: 
Now, in question we are given mean of 6 people that is 17
The age of 5 people are given while age of one person who enters the room is unknown.
Let age of person whose age is unknown= x
Now finding x using mean formula
So, The value of x: x=15
Hence, the age of the person who entered the room is 15
Answer:
17.5% per annum
Step-by-step explanation:
<u>Given:</u>
Money invested = $20,000 at the age of 20 years.
Money expected to be $500,000 at the age of 40.
Time = 40 - 20 = 20 years
<em>Interest is compounded annually.</em>
<u>To find:</u>
Rate of growth = ?
<u>Solution:</u>
First of all, let us have a look at the formula for compound interest.
Where A is the amount after T years compounding at a rate of R% per annum. P is the principal amount.
Here, We are given:
P = $20,000
A = $500,000
T = 20 years
R = ?
Putting all the values in the formula:
![500000 = 20000 \times (1+\frac{R}{100})^{20}\\\Rightarrow \dfrac{500000}{20000} =(1+\frac{R}{100})^{20}\\\Rightarrow 25 =(1+\frac{R}{100})^{20}\\\Rightarrow \sqrt[20]{25} =1+\frac{R}{100}\\\Rightarrow 1.175 = 1+0.01R\\\Rightarrow R \approx17.5\%](https://tex.z-dn.net/?f=500000%20%3D%2020000%20%5Ctimes%20%281%2B%5Cfrac%7BR%7D%7B100%7D%29%5E%7B20%7D%5C%5C%5CRightarrow%20%5Cdfrac%7B500000%7D%7B20000%7D%20%3D%281%2B%5Cfrac%7BR%7D%7B100%7D%29%5E%7B20%7D%5C%5C%5CRightarrow%2025%20%3D%281%2B%5Cfrac%7BR%7D%7B100%7D%29%5E%7B20%7D%5C%5C%5CRightarrow%20%5Csqrt%5B20%5D%7B25%7D%20%3D1%2B%5Cfrac%7BR%7D%7B100%7D%5C%5C%5CRightarrow%201.175%20%3D%201%2B0.01R%5C%5C%5CRightarrow%20R%20%5Capprox17.5%5C%25)
So, the correct answer is <em>17.5% </em>per annum and compounding annually.
the light bulb uses 8100 total watts
