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anuragbytes
1. A man pays off 3/20 of his debt every month.At the end of 6 months, his remaining debt is $A.How much amount has he cleared off every month?
(a) 3A/20
(b) 9A/10
(c) A/10
(d) 3A/10
(e) 3A/2
Let his total debt be T
Every month he pays off 3/20 of his debt = \(3/20 * T\)
After 6 months he would have paid = \(3/20 * 6 * T\)
His remaining debt after 6 months is A.
Hence Total debt = Remaining debt + Paid debt
\(T=A+3/20 * 6 * T\)
\(T-18/20 * T = A\)
\(T * 2/20 = A\)
\(T= 10A\)
Every month he pays off 3/20 of his debt = \(3/20 * T = 3/20 * 10 A = 3A/2\)
OA E.
anuragbytes
2. 3/5 part of a petrol tin is filled.If 6 bottles are taken out of it and 3 bottles are filled again, then half the tin is full. What is the capacity of the tin(in bottles)?
(a) 20
(b) 30
(c) 45
(d) 50
(e) 40
Let the capacity of tin in bottles be x
\(3/5 x - 6 + 3 =1/2 x\)
\(3/5 x - 1/2 x = 3\)
\(x/10 = 3\)
\(x= 30\)
OA B.
anuragbytes
3. It takes 40 days for a pond to get filled with rain water.If the level of water doubles each day, then how long would it take to fill 1/4 of the pond
(a) 10 days
(b) 20 days
(c) 30 days
(d) 35 days
(e) 38 days
Let the rate at which pond fills each DAY be x.
Water level doubles each day, hence
DAY LEVEL
1 x
2 2x
3 4x
4 8x
5 16x
Water level rises in a series which is geometric series with first term a=x and common ration r = 2
Also, it takes 40 days to fill the pond to its capacity.
According to series, the LEVEL of water in 40 days will be 40th term of the series.
\(a40 = x*2^(^40-1^)\)
\(a40= x * 2^3^9\)
Hence capacity of pond is = \(x*2^3^9\)
1/4 of that capacity = \(1/4 * x*2^3^9\)
=\(x*2^3^7\)
Now mere observation will tell you that LEVEL of pond on a given day is \(x*2^(^D^A^Y-^1^)\)
Like on day 4, level is 8x => \(2^(^4^-^1^)x\)
on day 5, level is 16x => \(2^(^5-^1^)x\)
On day 38, LEVEL will be =\(x * 2^(3^8-^1) = x*2^3^7.\)
Hence on 38th day pond will be 1/4 full.
OA E.