Answers

2015-11-18T17:00:50+05:30
I think the answer will be 640.
am i right

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2015-11-18T17:06:23+05:30
Initially it is 10
 means a=10
its grow double after 1o min interval
means if it is x then after 10 min it should be  2x then 2(2x) then 2(2(2x))) and so on ........... this show that it is in geometric progression
tn=ar^n-1 is formula to calculate number in n position
r=tn+1/tn=2(2x))/2x=2
10 min interval between 60 min.
60/10=6 
n=6+1( including initial 0 minute)
n=7
a=10 as we know through question
put all values in above formula
t7=10 X2^7-1
=10X64
=640
answer is 640
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