One of the most important and exam oriented question from Chapter name- Arithmetic Progression
Class 10th
Chapter number- 9
Exercise :- 9.4
This type of question has been asked in previous years exams.
In this question we have been given an arithmetic progression. And we have to find out how many terms are in this AP
CBSE DHANPAT RAI publication
Understanding CBSE Mathematics
Question 4(ii)
Given that,
A.P. -1, -5/6, -2/3, -1/2, … , 10/3
where, a = -1 and d = a2 – a1 = -5/6 – (-1) = 1/6
As we know that, to find nth term in an A.P = a + (n – 1)d
a + (n – 1)d = 10/3
-1 + (n – 1)(1/6) = 10/3
-1 + n/6 – 1/6 = 10/3
n/6 = 10/3 + 1 + 1/6
n/6 = (20 + 6 + 1)/6
n = (20 + 6 + 1)
n = 27
Hence, there are 27 terms in the given A.P.