Kumar writes a letter to four of his friends. He asks each one of them to copy the letter and mail to four different persons with the instruction that they continue the process similarly. Assuming that the process is unaltered and it costs Rs. 2 to mail one letter, find the amount spent on postage when 8th set of letters is mailed.
Answers
Answer:
Rs 131072
Rs 174760
Step-by-step explanation:
Kumar writes a letter to four of his friends. He asks each one of them to copy the letter and mail to four different persons with the instruction that they continue the process similarly. Assuming that the process is unaltered and it costs Rs. 2 to mail one letter, find the amount spent on postage when 8th set of letters is mailed.
4 , 4 *4 = 16 16*4 = 64 and so on
This is a GP
where a = 4 r = 4
8th Set = ar⁷ = 4 * 4⁷ = 4⁸ = 65536
Cost = 2 * 65536 = 131072 Rs
To find total Cost Till 8th set
Total Letters mailed
= a(r⁸ - 1)/(r-1)
= 4(4⁸-1)/(4-1)
= 4(65536 - 1)/3
= 87380
Cost = 2 * 87380 = 174760 Rs
Answer:174769
Step-by-step explanation:It is on GP so we will use An formula
Sn=a(r^n–1)/r–1
S8=2(4^8–1)/4–1
S8=2(65536–1)/3=2(65535)/3
S8=2×21845=43690
Cost of postage after posting 8th set of letter=4×43690
=174760