Question

1. what is 30% of 15?
2. 28 is 4% of what number?
3. find 28.5% of 200.
4. 7.5% of what number is 21?

Explanation:

Question 3: What is 30% of 15?

Step1: Convert percentage to decimal

To find a percentage of a number, first convert the percentage to a decimal. 30% is equivalent to $0.30$ (since $30\%=\frac{30}{100} = 0.30$).

Step2: Multiply the decimal by the number

Now, multiply this decimal by 15. So, $0.30\times15 = 4.5$.

Step1: Let the number be \( x \)

We know that 4% of \( x \) is 28. Mathematically, this can be written as \( 0.04x=28 \) (since 4% = 0.04).

Step2: Solve for \( x \)

To find \( x \), divide both sides of the equation by 0.04. So, \( x=\frac{28}{0.04}=700 \).

Step1: Convert percentage to decimal

First, convert 28.5% to a decimal. \( 28.5\%=\frac{28.5}{100}=0.285 \).

Step2: Multiply the decimal by 200

Now, multiply this decimal by 200. So, \( 0.285\times200 = 57 \).

Answer:

$4.5$

Question 5: 28 is 4% of what number?