Q. 65.0( 4 Votes )

# A man is em

Answer :

Given: Amount to be counted is Rs. 10710

To find: Time taken by man to count the entire amount

He counts at the rate of Rs. 180 per minute for half an hour or 30 minutes

Amount to be counted in an hour = 180 * 30 = Rs. 5400

Amount to be left = 10710 – 5400 = 5310

Sn = 5310

After an hour, rate of counting is decreasing at Rs. 3 per minute. This rate will form an A.P.

A.P. will be 177, 174, 171,……………………

Here a = 177 and d = 174 – 177 = –3

Formula used: where a is first term, d is common difference and n is number of terms in an A.P.

Therefore,    10620 = 3n(119 – n)  n2 – 59n – 60n + 3540 = 0

n(n – 59) – 60(n – 59) = 0

(n – 59)(n – 60) = 0

n = 59 or 60

We will take value of n = 59 as at 60th min he will count Rs.0

Therefore, total time taken by him to count the entire amount = 30 + 59 = 89 minutes

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation view all courses RELATED QUESTIONS :

If <img widRS Aggarwal - Mathematics

In a potatoRD Sharma - Mathematics

A man accepRD Sharma - Mathematics

A manufactuRD Sharma - Mathematics

A man savesRD Sharma - Mathematics

A carpenterRD Sharma - Mathematics

A man startRD Sharma - Mathematics

The income RD Sharma - Mathematics

If tn Mathematics - Exemplar

Fill in the blankMathematics - Exemplar