Exercise 8 C
Q1| Ex-8C | Class 7 | SChand Composite Maths | Ratio , Proportion ,
Unitary Method | Chapter 8 | myhelper
Question 1
100gm of butter make 14 cakes . How many cakes 150 gm make ?
Sol :
100gm of butter make= 14 cakes
1 gm------------= $\frac{14}{100}$
150 gm ---------------------= $\frac{14}{100} \times 150=21$ cakes
Q2| Ex-8C | Class 7 | SChand Composite Maths | Ratio , Proportion , Unitary Method | Chapter 8 | myhelper
Question 2
A plane flies 405 km on 90 liter of fuel .
(i) How much fuel is needed for 540km ?
(ii) How far can it go is 50 liters ?
Sol :
Plane files 405 km on = 90 liters
---------1 km ------- = $\frac{90}{405}$
-------540 km ------= $\frac{90}{405} \times 540$
=120 liters
(ii) In 90 liters it can fly = 405 km
-------1 liter --------- = $\frac{405}{90}$
-------50 liters ------= $\frac{405}{90} \times 50$
= 225km
Q3| Ex-8C | Class 7 | SChand Composite Maths | Ratio , Proportion , Unitary Method | Chapter 8 | myhelper
Question 3
16 articles cost Rs 72 . What will be the cost of 30 articles ? How
many articles can be bought for Rs 207 ?
Sol :
16 articles cost = Rs 72
1 article cost = $\frac{72}{16}$
30 article cost=$\frac{72}{16} \times 30$ = Rs 135
(ii) In Rs 72 articles bought = 16
---Rs 1 ------------ = $\frac{16}{72}$
----Rs 207 ---------= $\frac{16}{72} \times 207$
= 46 articles
Q4| Ex-8C | Class 7 | SChand Composite Maths | Ratio , Proportion , Unitary Method | Chapter 8 | myhelper
Question 4
A Journey of 552 km takes 6 days. How long will a journey o f 1012 km take.
If it is done at the same rate?
Sol :
A journey of 552 km takes = 6 days
-----------1km ------- = $\frac{6}{552}$
--------------1012 km ---------= $\frac{6}{552} \times 1012$
=11 days
Q5| Ex-8C | Class 7 | SChand Composite Maths | Ratio , Proportion , Unitary Method | Chapter 8 | myhelper
Question 5
Two and a half liters of paint is used to cover 725 sq m of area .
(i) How much will be required to paint 2001 sqm of area ?
(ii) How much area in sq m can be covered by 4.75 liters of paint?
Sol:
To cover 725 sq m area paint used = 2.5L
------------1 sq m --------= $\frac{2.5}{725}$
------------- 2001 sq m ---------=$\frac{25}{725} \times 2001$
= 6.9 L
(ii) 2.5 L point covers = 725sqm
1L --------------------= $\frac{725}{2.5}$
4.75 ---------------=$\frac{725}{25} \times \frac{4.75}{100} \times 10$
= 1377.5 sqm
Q6| Ex-8C | Class 7 | SChand Composite Maths | Ratio , Proportion , Unitary Method | Chapter 8 | myhelper
Question 6
$5 \frac{1}{4} m^{3}$ of copper sheet weight 1563kg. What will be weight
of $3 \frac{1}{2} \mathrm{~m}^{3}$ of sheet ?
Sol :
$\frac{21}{4}$ $m^{3}$ weight = 1563
1 $m^{3}$ -------------= $\frac{1563}{\frac{21}{4}}$
$\frac{7}{2} \mathrm{~m}^{3}$ weight = $1563 \times \frac{4}{21}
\times \frac{7}{2}$
= 1042 kg Answer
Q7| Ex-8C | Class 7 | SChand Composite Maths | Ratio , Proportion , Unitary Method | Chapter 8 | myhelper
Question 7
Harsh takes 150 steps in walking a distance of 125 meters .
(i) What distance would be cover in 360 steps?
(ii) How many steps would be needed to cover a distance of 120 m ?
Sol :
(i) Harsh takes 150 steps covers distance = 125 m
-----------------1 step ------------- = $\frac{125}{150}$
------------360 steps-------------= $\frac{125}{150} \times 360$
=300 m
(ii) 125 m distance covered in = 150 steps
1m ---------- = $\frac{150}{125}$
120m -----------------= $\frac{150}{125} \times 120$= 144 steps
Q8| Ex-8C | Class 7 | SChand Composite Maths | Ratio , Proportion , Unitary Method | Chapter 8 | myhelper
Question 8
Fifteen chairs can be bought for Rs 3532.50 . How many chairs can be bought
for Rs 5416.50 ?
Sol :
15 chairs can be bought for Rs 3532.50
Cost of Rs 3532.50 is = 15 chairs
---------Rs 1 ----------= $\frac{15}{3532.50}$
Chairs bought for = Rs 5416.50 = $\frac{15}{3532.50} \times 5416.50 .$
= 23 chairs Answer
Q9| Ex-8C | Class 7 | SChand Composite Maths | Ratio , Proportion , Unitary Method | Chapter 8 | myhelper
Question 9
45 packets of butter each weighing 100gm cost Rs 607.50 What be
the cost of 18 packets of butter each weighing 500 gm ?
Sol :
If each packet weighting 100
Weight of 45 packets = $45 \times 100=4500 \mathrm{gm}$
Weight 18 packets of each weight = $18 \times 500$
$9000 \mathrm{gm}$
$4500 \mathrm{gm} \text { butter cost }=Rs 607.50$
1gm-----------$=\frac{607.50}{4500}$
9000gm ------------ =$\frac{607.50}{4500} \times 9000$
= Rs 1215 answer
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