You visited us 3 times! Enjoying our articles? Unlock Full Access!

Byju's Answer

Other

Quantitative Aptitude

Mean

What is the a...

Question

What is the arithmetic mean of first 20 terms of an AP whose first term is 5 and 4th term is 20?

No worries! We‘ve got your back. Try BYJU‘S free classes today!

52.5

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

No worries! We‘ve got your back. Try BYJU‘S free classes today!

57.5

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is B 52.5
$a = 5, t_{4} = a + 3 d = 20 \Rightarrow d = 5$
A.M is the middle number =average of $10^{t h}$ & $11^{t h}$ number $= \frac{50 + 55}{2} = 52.5$
(or) $A . M = \frac{S n}{n} = \frac{1}{2} [2 a + (n - 1) d]$ where a=5, n =20, d=5 $\Rightarrow$ A.M =52.5

Suggest Corrections

Similar questions

Q. Find the sum of first n terms of an AP whose nth term is (5 − 6n). Hence, find the sum of its first 20 terms.

The sum of the $4^{t h}$ and $12^{t h}$ term of an arithmetic progression is $20$ . What is the sum of the first $15$ terms of the arithmetic progression?

Q. The first term of an

A P

whose

6^{t h}

terms is

5

and the

10^{t h}

terms is

9

is ____________.

Sum of first 20 terms of an AP is and its first term is 7. Find its $24^{t h}$ term.

Q. Find the

20

t h

term of the

A P

whose

7

t h

term is

24

less than the

11

t h

term . first term being

12

Join BYJU'S Learning Program

What is the arithmetic mean of first 20 terms of an AP whose first term is 5 and 4th term is 20?

The correct option is B 52.5a=5,t4=a+3d=20⇒d=5 A.M is the middle number =average of 10th & 11th number =50+552=52.5 (or) A.M=Snn=12[2a+(n−1)d] where a=5, n =20, d=5 ⇒ A.M =52.5

The correct option is B 52.5
$a = 5, t_{4} = a + 3 d = 20 \Rightarrow d = 5$
A.M is the middle number =average of $10^{t h}$ & $11^{t h}$ number $= \frac{50 + 55}{2} = 52.5$
(or) $A . M = \frac{S n}{n} = \frac{1}{2} [2 a + (n - 1) d]$ where a=5, n =20, d=5 $\Rightarrow$ A.M =52.5