The ratio of weights of two children is 3/4 and the difference of weigths is 3 kg. What is the fractional weight of the heavier child ?
Informal solution: Posssbile weights are 3 and 4 , 6 and 8 , 9 and 12 , 12 and 16 ... Third is O.K.
For the formal solution have a look at ry1.
3/5 - 1/2 = 1/10 .
Let Janet's allowance be AJ and Janet's AT. AJ/AT = 5/6. What is true for a year should also be valid for a
month since the rate is the same over the year. In a month Janet saves AT/12 which should be equal to (5xAT)/6xC . This says 1/12 = 5/6xC ...
These type of problems are more easily solved by trial and error. Just try the answers .
Let the amount of mixture be B at the beginning and E at the end. We have to find 2 equations:
1. E = B - 20 .
2. (3/10)xE + 20 = B/2.
Putting 1 in 2 we have (3/10)x(B-20) + 20 = B/2 which means B/2 - 3xB/10 = 14
In a second the machine does 1/16 ths of the whole lifting. After 15 seconds 1/16 ths of the work (w.r.t. the machine) remains.
The man does the work in 240 seconds. What the machine does in a second, he does in 240/16 = ... seconds . See ry1 also.
The last two are not very likely .
The first two are 7 and 8 and 43/5 is 8 3/5
5/(A+5) ≥ 1 1/2 . The first is certainly less than 1 as long as A is natural number.
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