Marks of 5 students are in the ratio 7:8:9:10:11, and their average is 90 . How many of the students scored more than 75?

Correct option is C

Step 1: Define Variables

Let the marks of the five students be 7x , 8x , 9x , 10x , 11x, given that they are in the ratio 7 : 8 : 9 : 10 : 11.

We are also given that their average marks = 90.

Step 2: Form an Equation Using the Average

The average formula is:

Total marks:    7x + 8x + 9x + 10x + 11x = 45x

Now, using the average:   45x​/5 = 90

                                             9x = 90

                                       x = 10

Step 3: Calculate the Actual Marks of Each Student

7x=7×10=70

8x=8×10=80

9x=9×10=90

10x=10×10=100

11x=11×10=110

Step 4: Count How Many Scored Above 75

Students who scored above 75:

• 80

• 90

• 100

• 110

Thus, 4 students scored more than 75.