Does anyone know the best way to solve this DS problem?
If m, r, x, and y are positive, is the ratio of m to r equal to the ratio of x to y?
(1) the ratio of m to y is equal to the ratio of x to r.
(2) the ratio of m + x to r + y is equal to the ratio of x to y.
The answer is B.
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prachipareekh
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Remember:
if p/q = r/s then
p+r/q+s = p/q = r/s
p-r/q-s = p/q = r/s
ps = qr
From statement(1): m/y = x/r -- insufficient we cannot find value of m/r
From statement(2): (m+x)/(r+y) = x/y
=> my+xy = xr+xy
=> my = xr
=> m/r = x/y -- sufficient
Hence ans B
if p/q = r/s then
p+r/q+s = p/q = r/s
p-r/q-s = p/q = r/s
ps = qr
From statement(1): m/y = x/r -- insufficient we cannot find value of m/r
From statement(2): (m+x)/(r+y) = x/y
=> my+xy = xr+xy
=> my = xr
=> m/r = x/y -- sufficient
Hence ans B
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moneyman
- Master | Next Rank: 500 Posts
- Posts: 468
- Joined: Sat Mar 03, 2007 10:17 pm
- Thanked: 5 times
If m, r, x, and y are positive, is the ratio of m to r equal to the ratio of x to y?
(1) the ratio of m to y is equal to the ratio of x to r.
(2) the ratio of m + x to r + y is equal to the ratio of x to y.
We have to find out if m/r=x/y which means we have to find out if my=xr
(1) is not sufficient because it says m/y=x/r or mr=xy
(2) is SUFFICIENT because it says m+x/r+y=x/y or ym+xy=rx+yx(by cross multiplying)
xy cancels on both sides and we get my=xr
(1) the ratio of m to y is equal to the ratio of x to r.
(2) the ratio of m + x to r + y is equal to the ratio of x to y.
We have to find out if m/r=x/y which means we have to find out if my=xr
(1) is not sufficient because it says m/y=x/r or mr=xy
(2) is SUFFICIENT because it says m+x/r+y=x/y or ym+xy=rx+yx(by cross multiplying)
xy cancels on both sides and we get my=xr
Maxx
