Q4 A. Find the ratio of 250 m to 5 km.
B. Convert the following ratios into percentages:
1) 3:15 2) 13:20
C. SOLVE: (Any 1 )
1) 30 % of 50 students are not good in mathematics. How many are good in mathematics?
2) If Haarish had Rs. 500 left after spending 80 % of his money, how much did he have in the beginning?
Answers
Answer:
4. A ) Ratio of 250 m to 5 km
Conversion Factor: 1 km = 1000 m
Therefore 5 km = 5000 m
Calculating ratio we get,
⇒ 250 m : 5000 m
⇒ 10 m : 200 m
⇒ 1 : 20
B ) Conversion Factor = ( Ratio × 100 ) = Percentage
⇒ 3 : 15 = 3/15
⇒ Percentage = ( 3/15 ) × 100
⇒ Percentage = ( 1/5 ) × 100 = 20 %
⇒ 13:20 = 13/20
⇒ Percentage = ( 13/20 ) × 100
⇒ Percentage = ( 1300 / 20 ) = 65 %
C ) 1 ) 30% of 50 students are not good in maths. This means that the rest 70% are good in maths.
⇒ Number of students good in maths = 70% of 50 students
⇒ Number of students = ( 70/100 ) × 50
⇒ Number of students = ( 3500/100 ) = 35 students
2 ) Let the original amount of money he had be Rs. x
After spending 80% he has 20% of his money left which is Rs. 500. This implies,
⇒ 20% of x = Rs. 500
⇒ ( 20/100 ) × x = Rs. 500
⇒ ( x / 5 ) = Rs. 500
⇒ x = Rs. 500 × 5
⇒ x = Rs. 2500
AnswEr :
A] Find the ratio of 250 m to 5 km.
➟ 250 m : 5 km
➟ 250 m : (5 × 1000) m
➟ 250 m : 5000 m
➟ 1 : 20
B] Convert the following ratios into percentages:
Percentage (%) = Ratio × 100
1) 3 : 15
➟ 3 / 15 × 100
➟ 1 / 5 × 100
➟ 20%
2) 13 : 20
➟ 13 / 20 × 100
➟ 13 × 5
➟ 65%
C] SOLVE: (Any 1 )
1) 30 % of 50 students are not good in mathematics. How many are good in mathematics?
Good = Total - Not Good
= 100% - 30%
= 70%
➟ Good Students in Mathematics
➟ 70% of 50
➟ 70 / 100 × 50
➟ 7 × 5
➟ 35
჻ 35 out of 50 Students are Good in Mathematics.
2) If Haarish had Rs. 500 left after spending 80 % of his money, how much did he have in the beginning?
•Let the Total Money in the Beginning be a
Left Amount = Total - Spend
= 100% - 80%
= 20%
➟ a × 20% = 500
➟ a × 20 / 100 = 500
➟ a × 1 / 5 = 500
➟ a = 500 × 5
➟ a = Rs. 2500
჻ Haarish have Total Rs. 2500 total Money.