The average of four numbers is 40. If the first number is one-third of the sum of the remaining numbers, then the first number is:

Question

Accepted Answer

1. **Given Data**:  
   - The average of four numbers is 40.  
   - The sum of all four numbers is:  
     $$
     	ext{Sum} = 4 	imes 40 = 160.
     $$  
   - The first number is one-third of the sum of the remaining three numbers.

2. **Let the First Number Be $$ a $$**:  
   The sum of the remaining three numbers is $$ 160 - a $$. According to the problem:  
   $$
   a = \frac{1}{3}(160 - a).
   $$

3. **Solve for $$ a $$**:  
   Multiply through by 3 to eliminate the fraction:  
   $$
   3a = 160 - a.
   $$  
   Simplify:  
   $$
   4a = 160 \implies a = \frac{160}{4} = 40.
   $$

4. **Conclusion**:  
   The first number is **40**.

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### Final Answer:
The correct option is **D. 40**.

Answer

Answer

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