Exercise 2M
Question 1
Find in cm, the height of a pile of books is each is 2 cm 3 mm thick.
Sol :
2cm 3mm=(2×10)mm+3mm
=(20+3)mm=23mm
Height of a pile of 15 books=(23×15)mm
=345mm
Question 2
A pile of 160 sheets is 6.08 cm high. Find in mm the thickness of one sheet.
Sol :
6.08cm=(6.08×10)mm
=60.8mm
Thickness of one sheet$=\frac{60.8}{160}$mm
=0.38mm
Question 3
How many pieces of tape each 6 cm long, can be cut from a length of 1 m 5 cm and how much remains?
Sol :
1m5cm=(100+5)cm
=105cm
Pieces of tape can be cut$=\frac{105}{6}$cm
=17 cm and 8 cm remaining
Ans: 17 pieces can be cut from tape and 3cm remaining
Question 4
How many jars each holding 1.75 kg of jam can be filled from a vessel containing 100 kg of jam and how much remains?
Sol :
Number of jars can be filled with jam$=\frac{100}{1.75}=\frac{10000}{175}$
=57 and 25 kg jam remaining
Ans: 57 jams can be filled with jam and 25kg jam remaining
Question 5
A racing car travels 425 m in 10 sec; express this speed in km per hour.
Sol :
9m10sec a car travels 425m
1 sec a car travels $\frac{425}{10}$
3600 sec a car travels $\frac{425 \times 3600}{10}$m
=153000=153km
Ans: 153km/hour
Question 6
A flask weighs 64.27 g when empty and 150.35 g when full of water. Find its weight when it is half full of water.
Sol :
Weight of water=(150.35-64.27)g=86.08g
Weight of flask when it is half full of water
$=\left(64.27+\frac{86.08}{2}\right)$g
=(64.27+43.04)g
=107.31g
Question 7
A square and an equilateral triangle have a side in common. If a side of the triangle is 15 mm long, find the perimeter of the figure given alongside in cm.
Sol :
Perimeter of equilateral triangle=(15×3)mm
=15mm=45cm
Ans : Perimeter of triangle 45cm
Question 8
Diameter of Earth is 12756000 m. A new plant was discovered whose diameter 5/86 of the diameter of Earth. Find the diameter of the planet of this planet in km.
Sol :
Diameter of new planet$=12756000\times \frac{5}{86}$m
=741627.907m or 741.628km
Ans : Diameter of this planet is 741.628km
Question 9
Ravindra is 144 cm tall. That is 9/10 as tall as his elder brother. How tall is Ravindra’s elder brother?
Sol :
Height of rabindra's elder brother$=\left(144 \div \frac{9}{10}\right)$cm
$=144 \times \frac{10}{9}$cm
=160 cm
Question 10
A public sewer line is being installed along 161/2 m of road. The supervisor says that the labourers will be able to complete 7.5 m in one day. How long will the project take to complete?
Sol :
Labours able of complete 7.5m in 1day
Labours able of complete 1m in $\frac{1}{75}$day
Labours able of complete $80\frac{1}{2}$m in $=\frac{10}{7.5}\times 80\frac{1}{2}$day
$=\frac{10}{75}\times \frac{161}{2}$
=10.73≅11
Ans : The project will take 11 days to complete
No comments:
Post a Comment