386. 80 / ? = ? / 20

1. 1. 40

   
   
   

   2. 400

   
   
   

   3. 800

   
   
   

   4. 1600

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Let 80/y = y/20
   Then, y ² = 80 x 20 = 1600
   

   Correct Option: A

   Let 80/y = y/20
   Then, y ² = 80 x 20 = 1600
   ∴ y = √1600 = 40.

---

387. Which number should replace both the asterisks in (* /21) x (*/189) = 1 ?

1. 1. 21

   
   
   

   2. 63

   
   
   

   3. 3969

   
   
   

   4. 147

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Let (y/21) x (y/189) = 1
   Then , y² = 21 x 189 = 21 x 21 x 9
   ∴ y = (21 x 3) = 63 .

   Correct Option: B

   Let (y/21) x (y/189) = 1
   Then , y² = 21 x 189 = 21 x 21 x 9
   ∴ y = (21 x 3) = 63 .

---

---

388. What least number must be subtracted from 13601 to get a number exactly divisible by 87 ?

1. 1. 49

   
   
   

   2. 23

   
   
   

   3. 29

   
   
   

   4. 31

   
   
   

---

1. View Hint View Answer Discuss in Forum

   29

   Correct Option: C

   On dividing 13601 by 86, we get 29 as remainder
   ∴ Required number to be subtracted = 29.

---

389. 392/√? = 28

1. 1. 144

   
   
   

   2. 196

   
   
   

   3. 24

   
   
   

   4. 48

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Let 392/√x = 28
   Then √x = 392/28 =14
   ⇒ x = 14² = 196
   

   Correct Option: B

   Let 392/√x = 28
   Then √x = 392/28 =14
   ⇒ x = 14² = 196
   

---

---

390. The sum of first four prime numbers is ?

1. 1. 10

   
   
   

   2. 11

   
   
   

   3. 16

   
   
   

   4. 17

   
   
   

---

1. View Hint View Answer Discuss in Forum

   First four prime numbers are 2,3,5,7,
   

   Correct Option: D

   First four prime numbers are 2,3,5,7,
   Their sum = (2 + 3 + 5 + 7) = 17.

---