CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

The sums of first n terms of two A.Ps are in the ratio (3n+8):(7n+15). The ratio of their 12th terms is

A
49
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
716
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
C
37
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
167
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is B 716
Thereare2ApwithdifferentfirsttermandcommondifferenceforthefirstAPletfirsttermbeacommondifferencebedsumofnterm=Sn=n2[2a+(n1)d]nthterm=an=a+(n1)dsimialrlyforsecondtermbe=Acommondifference=DSn=n2[2A+(n1)]Dnthterm=A+(n1)Da12offirstAPA12of2ndAP=a+(121)dA+(121)D=a+11dA+11Dgiventhatsumofntermsof1stAPsumofntermof2ndAP=3n+87n+15n2[2a+(n1)d]n2[2A+(n1)D]=3n+87n+152(a+(n12)d)2(A+(n12)D)=3n+87n+15a+(n12)dA+(n12)D=3n+87n+15(i)weneedtofinda+11dA+11Dn12=11n1=22n=23puttingnineq.(i)a+(2312)dA+(2312)D=3×23+87×23+15a+11dA+11D=77176a+11dA+11d=716Theratioof12thtermis716

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Arithmetic Progression - Sum of n Terms
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon