Question 460393
The average of 5 numbers is 48.The average of the first 3 numbers is 30.
 The fourth number is 20 more then the fifth number.
 What is the fourth number.
:
"The average of 5 numbers is 48"
{{{(a+b+c+d+e)/5}}} = 48
a + b + c + d + e = 5(48)
a + b + c + d + e = 240
:
"The average of the first 3 numbers is 30."
{{{(a+b+c)/3}}} = 30
a + b + c = 90
:
"The fourth number is 20 more then the fifth number."
d = (e+20)
e = (d-20)
:
In the 1st equation replace a+b+c with 90, replace e with (d-20)
90 + d + (d-20) = 240
2d = 240 - 70
2d = 170
d = {{{170/2}}}
d = 85 is the 4th number