Join 60,000+ competitive exam aspirants
or with email
Your Cart
Subtotal₹0
Total₹0
Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
Join 60,000+ competitive exam aspirants
If 15th and 28th terms of an A.P. be 208 and 416 respectively, then its 49th term is:
755
749
752
751
752
Use the property that the slope of the AP is constant: d = (a28 - a15) / (28 - 15) = 208 / 13 = 16. Then, a49 = a28 + (49 - 28)d = 416 + 21(16) = 416 + 336 = 752.
15th term (a15) = 208, 28th term (a28) = 416.
an=a+(n−1)d
Use the property that the slope of the AP is constant: d = (a28 - a15) / (28 - 15) = 208 / 13 = 16. Then, a49 = a28 + (49 - 28)d = 416 + 21(16) = 416 + 336 = 752.
Students often solve the system of linear equations for 'a' and 'd' individually, which is time-consuming compared to using the property of common difference d directly.
Calculate Common Difference
The common difference d can be found using the formula d=m−nam−an.
d=28−15416−208=13208=16
Calculate 49th term
Use the term relation a49=a28+(49−28)d to find the result.
a49=416+21×16=416+336=752
C is correct because calculating the common difference as 16 and applying the linear growth property yields 752.
This logic is identical to finding the equation of a line y=mx+c given two points, where the common difference d acts as the slope m.
Get instant step-by-step AI explanations, full shift Previous Year Papers (SSC GD, RRB, SSC JE), and regional rank analysis on the official Examoogle App.
Free Download • 100K+ Aspirants