The interest on a certain sum of money is Rs. 67.20 and the discount on the same of money for the same time and at the same rate is Rs. 60. What is sum?

Profit (%) = 9.09 % = 1/11

Since the ratio of water and milk is  1 : 11,

Therefore the ratio of water is to mixture = 1:12

Thus the quantity of water in mixture of 1 liter = 1000 x (1/12) = 83.33 ml

(a + b)/2 = 25
a + b = 50
?ab = 7
ab = 49
Hence, A can either be 7 or 49.
So, 49 is the answer.

P² + 4Q² = 4PQ
? P² + 4Q² - 4PQ = 0
? (P - 2Q)² = 0
? P - 2Q = 0
? P = 2Q
? P/Q = 2/1
? P : Q = 2 : 1

? Probability of machine failing during a day p = 0.95
? q = Probability of its working during a day = 1 - p = 1 - 0.95 = 0.05

Required probability = q⁴ = (0.05)⁴
= 0.00000625

Given that
A : B = 3 : 4 = ( 3 x 2 ) : (4 x 2 ) = 6 : 8
B : C = 8 : 9
? A : B : C = 6 : 8 : 9
As consequent of the first ratio is equal to the antecedent of second ratio.

Time from 6 am on a day to 11 pm on 4th day = 89 h
Now, 23 h 44 min of this clock = 24 h of correct clock
89 h of this clock = 24 x (15/356) x 89 h of correct clock = 90 h of correct clock
? Correct time will be 12 o' clock (mid-night).

Given that n = 2 and (n + 1) = 3(n < 6)
The hands will be at the same straight line at
? (5n + 30) x 12/11 min past n.
? (5 x 2 + 30 ) x 12/11 min past 2.
? (10 + 30) x 12/11 min past 2.
? 40 x 12/11 min past 2.
? 480/11 min past 2.

Required mean proportional = ?9 x 64
= 3 x 8 = 24

Let term = l = ar^{n - 1} a = 5 and l = 20480
r = 20/5 = 4
? 20480 = 5 x (4)^n-1
(4)^n-1 = 20480/5 = 4096 = (4)⁶
n - 1 = 6
? n = 7