Question

The average length of three tapes is 6800 feet. None of the tapes is less than 6400 feet. What is the greatest possible length of one of the other tapes?

Answer 1

The total value of the tapes 3(6800)=20400
If one is maximum, the other two must be minimum.
Maximum number is (20400-12800)=7600

Answer 2

7600 is the greatest possible length of one of the other tapes.

Given:  

Average length of three tapes = 6800  

None of them are less than 6400  

To find:  

Greatest possible length of one of the tapes?  

Solution:  

Total length of three tapes$= 3\times 6800$

                                                 $= 20400$

If one of the three is maximum, the other two will be less than the greater one and more than or equal to 6400.

So, length of the other two tapes will be $6400\times2 = 12800$

Therefore, the greatest possible length will be $\bold{20400 - 12800 = 7600}$