One hundred loaves of bread are to be divided among 5 people so that the amounts that they receive form an arithmetic sequence. The first two together receive one-seventh of what the last three receive. How many does each receive
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Suppose they get a, a+d, a+2d, a+3d, a+4d loaves.
So 5a+10d = 100 or a + 2d = 20..................(1)
From the given condition,
a+(a+d) = (1/7)[(a+2d)+ (a+3d) + (a+4d)]
which means 7[2a +d] = [3a+9d]....................(2)
Solve these 2 eqns simultaneouly to find a and d.
You should have said "The first two together receive one-seventh of what the last three receive TOGETHER"
let n represent the number of loaves given to the first person and m the value of the term to term difference. The the 5 people receive, in order, n, n+m, n+2m, n+3m, and n+4m loaves.
Adding, we get 5n + 10m = 100
and 7(2n +m) = 3n + 9m 14n + 7m = 3n + 9m
Solving we get 11n = 2m or 11n - 2m =0
solving this simultaneously with the first equation yields 60n=100 or n = 5/3
which yields m = 55/6
So they receive, in order 5/3, 65/6, 120/6 (=20), 175/6, and 230/6 (=115/3) loaves
Let the five receive the portions in teh following AP
(a - 2d), (a - d), a , (a + d), (a + 2d)
Then
(a - 2d) + (a - d) + a + (a + d) + (a + 2d) = 100
=> 5a = 100
=> a = 20
Now
(a - 2d) + (a - d) = 1/7 [a + (a + d) + (a + 2d)]
=> 11a = 24d
=> d = 11a/24
=> d = 9.17
Hence portions should be
(20 - 2*9.17), (20 - 9.17), 20 , (20 + 9.17), (20 + 2*9.17)
= 1.67, 10.83, 20, 29.17, 38.34