The numbers 3, 5, 7, 4 have frequencies x, x + 4, x – 3, x + 8. If their arithmetic mean is 4, the value of x is
Explanation
1. Set Up the Frequency Table
First, we list the values (xi) and their corresponding frequencies (fi):
| Value (xi) |
Frequency (fi) |
Product (fixi) |
| 3 |
x |
3x |
| 5 |
x+4 |
5(x+4)=5x+20 |
| 7 |
x−3 |
7(x−3)=7x−21 |
| 4 |
x+8 |
4(x+8)=4x+32 |
2. Calculate the Total Frequency (∑fi)
Sum all the frequency terms:
3. Calculate the Sum of Products (∑fixi)
Sum the products calculated in the table:
∑fixi=3x+(5x+20)+(7x−21)+(4x+32)
4. Use the Arithmetic Mean Formula
The arithmetic mean (xˉ) is given as 4. The formula is:
Substitute the values:
5. Solve for x
Cross-multiply to solve the equation:
Rearrange the terms (bring x terms to one side and constants to the other):
Final Answer
The value of x is 35.