9. In an examination, 72% of the total examinees passed. If the number ol
the total number of examinees.
10. After deducting a commission of 5%, a moped costs 15200. What is its gross value?
11. Gunpowder contains 75% of nitre and 10% of sulphur, and the rest of it is charcoal. Find
the amount of charcoal in 8 kg of gunpowder.
12. Chalk contains 3% of carbon, 10% of calcium and 12% of oxygen. Find the amount in grams
of each of these substances in 1 kg of chalk.
Answers
Answer:
9. Assume that 100 candidate took the examination.
In that 72% of them are passed =72 candidates
In that failed candidates =(100−72)=28
Number of candidates if 28 of them failed =100
Number of candidates if 392 of them failed =(100/28)×392
=1400
∴ the total number of examinees is 1400
10. let the gross value is X
commission of 5% of X = 5x/100
Given moped cost = 15200
According to the question:
=> X - 5x/100 = 15200
=> (100x - 5x)/100 = 15,200
=> 95x/100 = 15200
=> 95x = 1520000
=> X = 1520000/95
=> X = 16,000
The gross value is Rs 16000
11. According to the given problem,
Quantity of nitrate = 75%
Quantity of Sulphur = 10 %
Quantity of Charcoal = ( 100 - 75 - 10 ) %
= 100 - 85
= 15 %
Amount of Charcoal = 15 % of 8kg of gun powder
= 15% × 8 kg
= ( 15 /100 ) × 8 kg
= ( 120 / 100 ) kg
= 1.2 kg
Therefore,
Amount of Charcoal in 8kg gun powder = 1.2 kg
12. From the question,
The amount of chalk =1 kg=1000 g
We have,
Amount of carbon in it =3% of 1000 g
=(3/100)×1000
=(3×10)
=30 g
Amount of calcium in it =10% of 1000 g
=(10/100)×1000
=(10×10)
=100 g
Amount of oxygen in it =12% of 1000 g
=(12/100)×(1000)
=(12×10)
=120 g
Step-by-step explanation: