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# A Person 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 Instruction that They Move the Chain Similarly. Assuming that the Chain is Not Broken and that It Costs 50 Paise to Mail One Letter. Find the Amount Spent on the Postage When 8th Set of Letter is Mailed. - CBSE (Arts) Class 11 - Mathematics

ConceptArithmetic Progression (A.P.)

#### Question

A person 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 instruction that they move the chain similarly. Assuming that the chain is not broken and that it costs 50 paise to mail one letter. Find the amount spent on the postage when 8th set of letter is mailed.

#### Solution

The numbers of letters mailed forms a G.P.: 4, 42, … 48

First term = 4

Common ratio = 4

Number of terms = 8

It is known that the sum of n terms of a G.P. is given by

It is given that the cost to mail one letter is 50 paisa.

∴Cost of mailing 87380 letters  Rs 87380 xx 50/100 = Rs 43693

Thus, the amount spent when 8th set of letter is mailed is Rs 43690.

Is there an error in this question or solution?

#### APPEARS IN

NCERT Solution for Mathematics Textbook for Class 11 (2018 to Current)
Chapter 9: Sequences and Series
Q: 29 | Page no. 200
Solution A Person 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 Instruction that They Move the Chain Similarly. Assuming that the Chain is Not Broken and that It Costs 50 Paise to Mail One Letter. Find the Amount Spent on the Postage When 8th Set of Letter is Mailed. Concept: Arithmetic Progression (A.P.).
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