Question

Naina borrowed some money from her friend for which she paid a simple interest of Rs 360 for 2 years. If the interest was compounded annually then she would have had to pay Rs 400 as interest for the same period. Calculate the money that was borrowed by Naine.​

Answer 1

Answer:

Let the speed of the stream be skm/hr.

Speed of boat in still water =11km/hr

Speed of boat in upstream =(11−s)km/hr

Speed of boat in downstream =(11+s)km/hr

Distance =12km

Therefore

11−s

12

+

11+s

12

=2

4

3

hr

⇒

(11−s)(11+s)

12(11+s+11−s)

=

4

11

⇒

121−s

2

12×22

=

4

11

⇒

121−s

2

12×2

=

4

1

⇒96=121−s

2

⇒s

2

=25

⇒s=±5

Since speed cannot be negative, we take s=5

Therefore Speed of stream is 5km/hr