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Q:

A wheel that has 6 cogs is meshed with a larger wheel of 14 cogs. When the smaller wheel has made 21 revolutions, then the number of revolutions mad by the larger wheel is:

A) 4 B) 9
C) 12 D) 49
 
Answer & Explanation Answer: B) 9

Explanation:

Let the required number of revolutions made by larger wheel be x.

 

Then, More cogs, Less revolutions (Indirect Proportion)

 

  14 : 6 :: 21 : x => 14 x x = 6 x 21

 

x=6*21/14  =>  x=9

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Filed Under: Chain Rule

Q:

 4 mat-weavers can weave 4 mats in 4 days. At the same rate, how many mats would be woven by 8 mat-weavers in 8 days?

A) 16 B) 12
C) 8 D) 4
 
Answer & Explanation Answer: A) 16

Explanation:

Let the required number of bottles be x.

 

More weavers, More mats (Direct Proportion)

 

More days, More mats (Direct Proportion)

 

 

weavers  4:8} :4:xdays        4:8}:4:x 

4 x 4 x x = 8 x 8 x 4

 

=> x = 8*8*44*4

 

=> x = 16.

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Filed Under: Chain Rule

Q:

A fort had provision of food for 150 men for 45 days. After 10 days, 25 men left the fort. The number of days for which the remaining food will last, is:

A) 29/5 B) 37/4
C) 42 D) 54
 
Answer & Explanation Answer: C) 42

Explanation:

After 10 days : 150 men had food for 35 days.

 

 

 

Suppose 125 men had food for x days.

 

 

 

Now, Less men, More days (Indirect Proportion)

 

 

 

 125 : 150 :: 35 : x    =>    125 x x = 150 x 35

 

 

 

 =>

 

 

 

=> x = 42.

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Q:

If the cost of x metres of wire is d rupees, then what is the cost of y metres of wire at the same rate?

A) Rs. (xy/d) B) Rs. (xd)
C) Rs. (yd) D) Rs. (yd/x)
 
Answer & Explanation Answer: D) Rs. (yd/x)

Explanation:

Cost of x metres = Rs. d.

Cost of 1 metre = Rs.(d/x)

Cost of y metres = Rs.[(d/x).y] = Rs.(yd/x)

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Filed Under: Chain Rule

Q:

If a quarter kg of potato costs 60 paise, how many paise will 200 gm cost?

A) 48 paise B) 54 paise
C) 56 paise D) 72 paise
 
Answer & Explanation Answer: A) 48 paise

Explanation:

Let the required weight be x kg.

 

 

 

Less weight, Less cost (Direct Proportion)

 

 

 

 250 : 200 :: 60 : x   =>    250 x x = (200 x 60)

 

 

 

=>

 

 

 

=> x = 48.

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Q:

4 mat-weavers can weave 4 mats in 4 days. At the same rate, how many mats would be woven by 8 mat-weavers in 8 days?

A) 4 B) 8
C) 12 D) 16
 
Answer & Explanation Answer: D) 16

Explanation:

Let the required number of bottles be x.

 

 

 

More weavers, More mats (Direct Proportion)

 

 

 

More days, More mats (Direct Proportion)

 

 

 

Wavers   4:8Days       4:8  :: 4:x

 

 

 

 4 x 4 x x = 8 x 8 x 4

 

 

 

=> x= 8*8*44*4

 

 

 

=>  x = 16.

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Q:

Two ships are sailing in the sea on the two sides of a lighthouse. The angle of elevation of the top of the lighthouse is observed from the ships are 30º and 45º respectively. If the lighthouse is 100 m high, the distance between the two ships is:

A) 173 m B) 200 m
C) 273 m D) 300 m
 
Answer & Explanation Answer: C) 273 m

Explanation:

 Let AB be the lighthouse and C and D be the positions of the ships.

 

 

Then, AB = 100m, ACB = 30°andADB =45°

 

ABAC=tan30°=13=>AC=AB*3=1003m

 

 

 ABAD=tan45°=1=>AD=AB=100m

CD=(AC+AD)=1003+100m=1003+1=100*2.73=273m

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Filed Under: Height and Distance

Q:

A group of students decided to collect as many paise from each member of group as is the number of members. If the total collection amounts to Rs. 59.29, the number of the member is the group is:

A) 57 B) 67
C) 77 D) 87
 
Answer & Explanation Answer: C) 77

Explanation:

Money collected = (59.29 x 100) paise = 5929 paise.

 

  Number of members = 5929 = 77.

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