**1.) **Find the average of all prime numbers between 30 and 50?

**A.** 26.25 **B.** 39.8

**C.** 37.75 **D.** None of these

**View Answer**

**Answer:** Option **B**

**Explanation**

There are five prime numbers between 30 and 50.

They are 31,37,41,43 and 47.

Therefore the required average= (31+37+41+43+47)/5

==> 199/5 ==> **39.8.**

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**2.) **Find the average of first 40 natural numbers?

**A.** 27.5 **B.** 19.8

**C.** 20.05 **D.** None of these

**View Answer**

**Answer:** Option **C**

**Explanation**

Sum of first n natural numbers=n (n+1)/2;

So, Sum of 40 natural numbers= (40*41)/2 ==> 820.

Therefore the required average= (820/40) ==> **20.5.**

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**3.) **Find the average of first 20 multiples of 7?

**A.** 22.66 **B.** 73.5

**C.** 37.75 **D.** None of these

**View Answer**

**Answer:** Option **B**

**Explanation**

Required average =7(1+2+3+……. +20)/20

==> (7*20*21)/ (20*2)

==> (147/2)=**73.5.**

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4.) The average of four consecutive even numbers is 27. find the largest of these numbers?

**A.** 19 **B.** 27

**C.** 30 **D.** None of these

**View Answer**

**Answer:** Option **C**

**Explanation**

Let the numbers be x, x+2, x+4 andx+6. Then,

(x+(x+2)+(x+4)+(x+6))/4) = 27

==> (4x+12)/4 = 27

==> x+3=27 à x=24.

Therefore the largest number=(x+6) =24+6=**30.**

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5.) There are two sections A and B of a class consisting of 36 and 44 students respectively. If the average weight of section A is 40kg and that of section B is 35kg, find the average weight of the whole class?

**A.** 22.66 kg **B.** 73.5 kg

**C.** 37.25 kg **D.** None of these

**View Answer**

**Answer:** Option **C**

**Explanation**

Total weight of(36+44) students=(36*40+44*35)kg =2980kg.

Therefore weight of the total class=(2980/80)kg =** 37.25kg.**

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