fluke wrote:
AnkitK wrote:
What is the range of a set consisting of the first 100 multiples of 7 that are greater than 70?
A.693
B.700
C.707
D.777
E.847
\(a_1=77\)
\(a_{100}=77+(99)*7=693+77\)
Range = 693+77-77=693
Ans: "A"
why is
99 is multiplied by 7?[/quote]
In an arithmetic progression
\(A_n=A_1+(n-1)*d\)
{77,84,91,98,.....,}
\(A_1=First \hspace{2} term=77\)
\(d=Common \hspace{2} Difference=7\)
\(A_{100}=A_1+(n-1)*d\)
\(A_{100}=77+(100-1)*7\)
\(A_{100}=77+99*7\)
\(A_{100}-A_1=77+99*7-77=99*7\)[/quote]
Hey fluke
i did it bit simpler
without any condition highest no among the first 100 multiple would be 100 x 7 =700
and highest among the first 10 multiple would be 10 x 7 = 70
so if we want to skip the first 10 multiple then we just need to add 70 to the previous 700 right?
it came 770 and now first multiple greater than 70 is simply 77
so answer is 770-77 = 693
please guide me if i am right