181. The number of students appeared from a school for the Madhyamik Examination in three consecutive years are in the ratio 7 : 8 : 10 and 75%, 87.5% and 93.75% of the students of respective years were successful. What is the percentage of students who were successful during these three years taken together ?

1. 1. 85.5%

   
   
   

   2. 86.5%

   
   
   

   3. 87%

   
   
   

   4. 88.5%

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Number of successful students :
   

   First Year ⇒	7x × 75	=	21x	= 5.25x
   	100		4

   
   

   Second year ⇒	8x × 87.5	= 7x
   	100

   
   

   Third year ⇒	10x × 93.75	= 9.375x
   	100

   
   Total successful students
   = 21.625x
   Required percentage
   

   =	21.625x	× 100 = 86.5%
   	25x

   Correct Option: B

   Number of successful students :
   

   First Year ⇒	7x × 75	=	21x	= 5.25x
   	100		4

   
   

   Second year ⇒	8x × 87.5	= 7x
   	100

   
   

   Third year ⇒	10x × 93.75	= 9.375x
   	100

   
   Total successful students
   = 21.625x
   Required percentage
   

   =	21.625x	× 100 = 86.5%
   	25x

---

182. An alloy contains 89% of copper; find how much copper is to be mixed to a sample of alloy so as to get 44 kg of a new metal having 90% copper in it.

1. 1. 2 kg

   
   
   

   2. 3 kg

   
   
   

   3. 2.5 kg

   
   
   

   4. 4 kg

   
   
   

---

1. View Hint View Answer Discuss in Forum

   In 100 gm of alloy, Copper = 89 gm.
   Let x gm. of copper be mixed
   

   	789 + x	=	90
   	11		10

   
   ⇒ x = 99 – 89 = 10gm
   To get 44 kg of new alloy, copper to be mixed
   

   =	44 × 1000 × 100	= 4 kg.
   	1100

   Correct Option: D

   In 100 gm of alloy, Copper = 89 gm.
   Let x gm. of copper be mixed
   

   	789 + x	=	90
   	11		10

   
   ⇒ x = 99 – 89 = 10gm
   To get 44 kg of new alloy, copper to be mixed
   

   =	44 × 1000 × 100	= 4 kg.
   	1100

---

---

183. If the numerator of a fraction is increased by 150% and the denominator of the fraction is increased by 300% the resultant fraction is
     

     5

     18

     
     What is the original fraction?

1. 1. 4

      9

   
   
   

   2. 8

      9

   
   
   

   3. 6

      9

   
   
   

   4. None of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Let original fraction be	x	.
   	y

   
   

   ∴	x × 250	=	5
   	y × 400		18

   
   

   ⇒	x	=	5	×	400	=	4
   	y		18		250		9

   Correct Option: A

   Let original fraction be	x	.
   	y

   
   

   ∴	x × 250	=	5
   	y × 400		18

   
   

   ⇒	x	=	5	×	400	=	4
   	y		18		250		9

---

184. An alloy of gold and silver weighs 50 gm. It contains 80% gold. How much gold should be added to the alloy so that percentage of gold is increased to 90?

1. 1. 45 gm

   
   
   

   2. 40 gm

   
   
   

   3. 50 gm

   
   
   

   4. None of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   In original alloy,
   Gold = 40 gm
   Silver = 10 gm
   Let x gm of gold is added.
   

   ∴	40 + x	=	90	=	9
   	50 + x		100		10

   
   ⇒ 400 + 10x = 450 + 9x
   ⇒ x = 50 gm.

   Correct Option: C

   In original alloy,
   Gold = 40 gm
   Silver = 10 gm
   Let x gm of gold is added.
   

   ∴	40 + x	=	90	=	9
   	50 + x		100		10

   
   ⇒ 400 + 10x = 450 + 9x
   ⇒ x = 50 gm.

---

---

185. 5% of income of A is equal to 15% of income of B and 10% of income of B is equal to 20% of income of C. If income of C is 2000, then total income of A, B and C is:

1. 1. 26,000

   
   
   

   2. 16,000

   
   
   

   3. 18,000

   
   
   

   4. 20,000

   
   
   

---

1. View Hint View Answer Discuss in Forum

   	A × 5	=	B × 15
   	100		100

   
   

   ⇒	A	=	15	=	3
   	B		5		1

   
   

   Again,	B × 10	=	C × 20
   	100		100

   
   

   	B	=	2
   	C		1

   
   ∴ A : B = 3 : 1 = 6 : 2
   B : C = 2 : 1
   ∴ A : B : C = 6 : 2 : 1
   ∴ Total income = 9 × 2000 = Rs. 18000

   Correct Option: C

   	A × 5	=	B × 15
   	100		100

   
   

   ⇒	A	=	15	=	3
   	B		5		1

   
   

   Again,	B × 10	=	C × 20
   	100		100

   
   

   	B	=	2
   	C		1

   
   ∴ A : B = 3 : 1 = 6 : 2
   B : C = 2 : 1
   ∴ A : B : C = 6 : 2 : 1
   ∴ Total income = 9 × 2000 = Rs. 18000

---