Answer these questions with solution
(i) Reena takes 4 hours in walking a distance of 20 km. What distance would she cover in 7 hours?
(ii) Find the amount on Rs. 4000 at 10%p.a. for 2 years, compounded annually.
(iii) A water pipe is cut into two pieces. The longer piece is 70% of the length of the pipe. By how much per cent is the longer piece longer than the shorter piece?
Answers
Answer:
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If Reena takes 4 hours to walk 20 km
=> 1 hour = 20/4
=> 1 hour = 5 km
So for 7 hours,
=> 7 hours x 5 km
=> 35km
Therefore in 7 hours she would walk 35 km.
Principal (P)=Rs.4000
Rate of Interest (r)=10%
Time =2 years and 3 months
Here, first we take n=2 years
A=P(1+
100
r
)
n
Where,
A= Amount and n= number of years
⇒A=4000(
10
11
)
2
⇒A=4000×
100
121
⇒A=Rs.4840
The Amount after two years =Rs.4840
Now,
Principal =Rs.4840
Simple interest for last 3 month, i.e.,
4
1
year =
100
PRT
=
100
4840×10×
4
1
=Rs.121
Therefore,
Amount after 2 years and 3 months =4840+121=Rs.4961
Therefore,
C.I.=A−P
⇒C.I.=4961−4000=Rs.961
Hence the compound interest is Rs.961.
olutions :-
Given :
A water pipe is cut into two pieces.
The longer piece is 70% of the length of the pipe.
Let the total length of water pipe be 100 m
Therefore,
Length of longer piece = 70% of 100 m
= 70 m
Shorter piece = (100 - 70) m = 30 m
The longer piece longer than the shorter piece = (70 - 30) m = 40 m
Find percent is the longer piece longer than the shorter piece :-
= ( 40 × 100)/30 %
= 4000/30 %
= 133.33 % approx.
Hence,
133.33 % is the longer piece longer than the shorter piece.