Question:
In a class, there are 40 students. Their average marks in a test are 33. If the average marks of the boys are 30 and that of the girls are 35, then what is the number of boys in the class?
In a class, there are 40 students. Their average marks in a test are 33. If the average marks of the boys are 30 and that of the girls are 35, then what is the number of boys in the class?
Show Hint
Weighted average formula
Updated On: Apr 21, 2026
- 15
- 20
- 16
- 18
Show Solution
Verified By Collegedunia
The Correct Option is C
Solution and Explanation
Step 1: Define variables.
Let number of boys = \(b\).
Then number of girls = \(40 - b\). Step 2: Write total marks in two ways.
Total marks = \(30b + 35(40 - b)\).
Also total marks = average × total students = \(33 \times 40 = 1320\). Step 3: Form equation.
\(30b + 1400 - 35b = 1320\).
\(-5b + 1400 = 1320\).
\(-5b = -80\).
\(b = 16\).
Let number of boys = \(b\).
Then number of girls = \(40 - b\). Step 2: Write total marks in two ways.
Total marks = \(30b + 35(40 - b)\).
Also total marks = average × total students = \(33 \times 40 = 1320\). Step 3: Form equation.
\(30b + 1400 - 35b = 1320\).
\(-5b + 1400 = 1320\).
\(-5b = -80\).
\(b = 16\).
Was this answer helpful?
0
0
Top NCHMCT JEE Quantitative Aptitude Questions
- The area of a rectangle having sides in the ratio 1 : 4 is equal to the area of a square of side 8 cm. The perimeter of the rectangle (in cm) is:
- If the mean of the observations 6, 16, \( (K + 26) \), \( (2K - 3) \), and 10 is 14, then the value of \( \frac{K^2 + 1}{2} \) is:
- If the length of the diagonal and the area of a rectangle are 25 m and 168 m\(^2\), respectively, then the longer side of the rectangle is:
- A and B, working together, can do a work in 8 days. If A alone can do the work in 12 days, then in how many days can B alone do 25 percent of the work?
- The sum of all possible values of \( K \) such that a 5-digit number 90K68 is divisible by 8 will be:
View More Questions
Top NCHMCT JEE Averages Questions
- In a class of 60 students, 60% are boys. The average of marks of the boys is 68 and that of the girls is 72. What are the average marks of the whole class?
- What is the average of first 16 multiples of 9?
- The average of the first 100 positive integers is:
- The average of 7 consecutive numbers is 20. The largest of these numbers is:
- If the mean of the observations k, (k+8), (2k-1), (k+12), 12 and 17 is 13, then find the median of these observations.
View More Questions
Top NCHMCT JEE Questions
- You find a person entering your restaurant in a wheelchair, you will:
- As a manager, you notice there has been repeated customer complaints against the smell of the carpet in a particular room, you will:
- Discipline, hard work, and dedication are the essential requirements to be a successful hotel operator. Upon getting this information, you would:
- As a teacher, you have been asked to select a team for Annual Day Celebration. You would select students:
- You are working in a hotel, a fire breaks out. You would:
View More Questions