Central Tendency & DispersionMTP June 2023 Series IIQuestion 2921 of 473
All Questions

A student marks were wrongly entered as 85\displaystyle 85 instead of 45\displaystyle 45. Due to that the average marks for the whole class got increased by one-fourth. The no. of students in the class is?

Options

A80
B160
C40
D20
For any discrepancies in this question, email contact@cadada.in

Correct Answer

✅ Option b — 160

All Options:

  • A80
  • B160
  • C40
  • D20

Detailed Solution & Explanation

**Step 1: Compute the error introduced.** Wrong entry: 85, Correct entry: 45. Excess added =85−45=40\displaystyle = 85 - 45 = 40. **Step 2: This excess caused average to increase by 14\displaystyle \frac{1}{4}.** Let n\displaystyle n = number of students. Increase in average =40n=14\displaystyle = \frac{40}{n} = \frac{1}{4} **Step 3: Solve for n\displaystyle n.** n=40×4=160n = 40 \times 4 = 160 **Note:** The computed number of students is **160** (Option B), not 40 (Option C). Hence, **Option B** is the correct answer.

More Questions from Central Tendency & Dispersion

If the range of 28,22,40,20,15,50\displaystyle 28, 22, 40, 20, 15, 50 is

If the S.D. of the 1st\displaystyle 1^{st} n\displaystyle n natural numbers is 30\displaystyle \sqrt{30} then the value of n\displaystyle n is

If the variance of 5,7,9\displaystyle 5, 7, 9 and 11\displaystyle 11 is 4\displaystyle 4, then the coefficient of variation is:

A helicopter flies from A to B at the rate of 500 km/hr. and comes back at the rate 700 km/hr. The average speed of the helicopter is

If Arithmetic Mean (A.M.) and Geometric Mean (G.M.) of two numbers are 6.50 and 6 respectively, then the two numbers are

Which of the following is not a method of dispersion?

Ready to Master Central Tendency & Dispersion?

Practice all 473 questions with instant feedback, earn XP, track your streaks, and ace your CA Foundation exam.

Start Practicing — It's Free