SOLUTION: the average of four numbers is 638.4 the first four numbers are 216 159.8 and 301.25 Find the fourth number.

Question 163277: the average of four numbers is 638.4 the first four numbers are 216 159.8 and 301.25 Find the fourth number.
Found 2 solutions by edjones, orca:
Answer by edjones(8007) (Show Source): You can put this solution on YOUR website!
216+159.8+301.25+x=638.4*4
677.05+x=2553.6
x=2553.6-677.05
x=1876.55
.
Ed
Answer by orca(409) (Show Source): You can put this solution on YOUR website!
Let the fourth number be x.
Then the average of the four number can be expressed as:

As the average is 638.4, we have

Solving the equation for x, we obtain

(multiply both sides by 4)

RELATED QUESTIONS
If the average of four numbers is 25, and three of the numbers are 24, what is the fourth (answered by oscargut)
the average of four numbers is 638.4 the first three numbers are 216,159.8,301.25. what... (answered by stanbon)
the average of the first three numbers is double of the fourth number. if the average of... (answered by jsmallt9)
In seven given numbers, the average of first four numbers is 4 and that of the last four... (answered by ikleyn)
the average of 5 numbers is 10. the first four numbers are 8, 9, 10, 11. find the fifth... (answered by FrankM,stanbon)
the average of first three numbers is double from fourth no. if the average of all four... (answered by god2012)
The sum of four numbers is 100. The average of first, second and fourth is 24. Difference (answered by ewatrrr)
four numbers add up to 95. The second number is twice the first number, the third number... (answered by josmiceli)
four numbers add up to 95. The second number is twice the first number, the third number... (answered by dkppathak)