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Q:

A, B and C start at the same time in the same direction to run around a circular stadium. A completes a round in 252 seconds, B in 308 seconds and c in 198 seconds, all starting at the same point. After what time will they again at the starting point ?

A) 26 minutes and 18 seconds	B) 42 minutes and 36 seconds
C) 45 minutes	D) 46 minutes and 12 seconds

Answer & Explanation Answer: D) 46 minutes and 12 seconds

Explanation:

L.C.M. of 252, 308 and 198 = 2772.

So, A, B and C will again meet at the starting point in 2772 sec. i.e., 46 min. 12 sec.

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Filed Under: Quantitative Aptitude - Arithmetic Ability

Q:

The greatest number which on dividing 1657 and 2037 leaves remainders 6 and 5 respectively, is:

A) 123	B) 127
C) 235	D) 305

Answer & Explanation Answer: B) 127

Explanation:

Required number = H.C.F. of (1657 - 6) and (2037 - 5)

= H.C.F. of 1651 and 2032 = 127.

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Filed Under: HCF and LCM

Q:

Three number are in the ratio of 3 : 4 : 5 and their L.C.M. is 2400. Their H.C.F. is:

A) 40	B) 80
C) 120	D) 200

Answer & Explanation Answer: A) 40

Explanation:

Let the numbers be 3x, 4x and 5x.

Then, their L.C.M. = 60x.

So, 60x = 2400 or x = 40.

The numbers are (3 x 40), (4 x 40) and (5 x 40).

Hence, required H.C.F. = 40.

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Filed Under: HCF and LCM

Q:

Six bells commence tolling together and toll at intervals of 2, 4, 6, 8 10 and 12 seconds respectively. In 30 minutes, how many times do they toll together ?

A) 4	B) 10
C) 15	D) 16

Answer & Explanation Answer: D) 16

Explanation:

L.C.M. of 2, 4, 6, 8, 10, 12 is 120.

So, the bells will toll together after every 120 seconds(2 minutes).

In 30 minutes,they will together (30/2)+1=16 times

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Filed Under: HCF and LCM

Q:

Find the ratio in which rice at Rs. 7.20 a kg be mixed with rice at Rs. 5.70 a kg to produce a mixture worth Rs. 6.30 a kg.

A) 1:3	B) 2:3
C) 3:4	D) 4:5

Answer & Explanation Answer: B) 2:3

Explanation:

By the rule of alligation:
Cost of 1 kg rice of 1st kind Cost of 1 kg rice of 2nd kind

Required ratio = 60 : 90 = 2 : 3

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Filed Under: Alligation or Mixture

Q:

A vessel is filled with liquid, 3 parts of which are water and 5 parts of syrup. How much of the mixture must be drawn off and replaced with water so that the mixture may be half water and half syrup?

A) 1/3	B) 1/4
C) 1/5	D) 1/7

Answer & Explanation Answer: C) 1/5

Explanation:

Suppose the vessel initially contains 8 litres of liquid.

Let x litres of this liquid be replaced with water.
Quantity of water in new mixture = $(3 - \frac{3 x}{8} + x)$ litres.

Quantity of syrup in new mixture = $(5 - \frac{5 x}{8})$ litres.

$(3 - \frac{3 x}{8} + x) = (5 - \frac{5 x}{8})$

=> 5x + 24 = 40 - 5x

=> 10x = 16 => x = 8/5

So, part of the mixture replaced = $(\frac{8}{5} \times \frac{1}{8})$ = 1/5.

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Filed Under: Alligation or Mixture

Q:

Two vessels A and B contain spirit and water in the ratio 5 : 2 and 7 : 6 respectively. Find the ratio in which these mixture be mixed to obtain a new mixture in vessel C containing spirit and water in the ration 8 : 5 ?

A) 4:3	B) 3:4
C) 5:6	D) 7:9

Answer & Explanation Answer: D) 7:9

Explanation:

Let the C.P. of spirit be Re. 1 litre.
Spirit in 1 litre mix. of A = 5/7 litre, C.P. of 1 litre mix.
in A = Re. 5/7
Spirit in 1 litre mix. of B = 7/13 litre, C.P. of 1 litre mix.
in B = Re. 7/13
Spirit in 1 litre mix. of C = 8/13 litre, Mean price = Re. 8/13.

By the rule of alligation, we have:
Cost of 1 litre mixture in A Cost of 1 litre mixture in B

Required ratio = 1/13 : 9/91 = 7:9.

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Filed Under: Alligation or Mixture

Q:

A container contains 40 litres of milk.From this container 4 litres of milk was taken out and replaced by water. This process was repeated further two times. How much milk is now contained by the container.

A) 26.34 litres	B) 27.36 litres
C) 28 litres	D) 29.16 litres

Answer & Explanation Answer: D) 29.16 litres

Explanation:

Amount of milk left after 3 operations

$(40 {(1 - \frac{4}{40})}^{3}) = (40 * \frac{9}{10} * \frac{9}{10} * \frac{9}{10}) = 29.16$ litres

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Filed Under: Alligation or Mixture

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