The ratio of boys to girls in a class is 7 to 3. Among the options below, an acceptable value for the total number of students in the class is:
Ratio Understanding
The ratio of boys to girls is given as 7 to 3 (7:3). This means that for every group of students represented by this ratio, there are 7 parts boys and 3 parts girls.
Calculating Total Parts
The total number of parts in the ratio is the sum of the parts for boys and girls:
$ \text{Total Parts} = 7 (\text{boys}) + 3 (\text{girls}) = 10 \text{ parts} $
Determining Acceptable Total Students
The total number of students in the class must be divisible by the total number of parts (10). This ensures that the number of boys and girls are whole numbers, maintaining the 7:3 ratio.
We need to find which option is a multiple of 10:
- Option 1: 21 is not divisible by 10.
- Option 2: 37 is not divisible by 10.
- Option 3: 50 is divisible by 10 ($50 \div 10 = 5$).
- Option 4: 73 is not divisible by 10.
Therefore, 50 is the only acceptable value for the total number of students.
Important Questions from Ratio and Proportion
In a mixture of 156 litres, the ratio of milk and water is 7 : 6. How much water should be added to make the ratio 14 : 13?
If the ratio of the first to second number is 3 : 4 and that of the second to the third number is 8 : 5, and sum of three numbers is 190 then the third number is:
The third proportional to 9 and 15 is:
The average age of 3 persons is 30 years.If their ages are in the ratio of 3 : 5 : 7 respectively, then the age of the eldest person is:
The income of A and B are in the ratio 5 : 3. The expenses of A, B and C are in the ratio of 8 : 5 : 2. If C spends 2000 and B saves ₹ 700, then A saves:
