Learn to Calculate Average for RBI Grade B Phase 1 Exam

If we take a look at previous exams, we’ll find that average questions usually comprise 2 to 4 of all the questions asked on the Quant section of the RBI Grade B Phase 1 exam. This comes to about 7 to 13% of the Quantitative Aptitude section. That makes this topic worth mastering. In this blog, you’ll get the most important formulas. You’ll learn smart tricks to solve average questions fast. You’ll also get simple examples with full steps. By the end, you’ll tackle average questions with ease and confidence.

ALSO READ: How to Score Maximum Marks in Cloze Test

What Is Average?

Average/or mean is the central value of a group of numbers.
Formula:

Average = (Sum of values) divided by (Number of values).

This idea pops up in many types of questions:

• Find a missing number.
• Work with group averages.
• Compare inside and outside values.

Before you move on, you must know the main formulas that are essential to solving such questions.

Main Formulas to Remember

Given below are the formulae that you must learn by heart and learn to apply them through regorous practice:

Simple Average

Sum = Average × Count.

If the average is 40 for 5 numbers, then, the total is 40 × 5 = 200.

Total using average

Total Sum = Average multiplied by Number of terms.

Weighted average

When values have different weights:

Average = (Sum of (value × weight)) divided by (Sum of weights).

Group average trick

If Group A has avg 30 for 10 items and Group B has avg 50 for 20 items:

Combined avg = (30×10 + 50×20) ÷ (10+20) = (300 + 1000) ÷ 30 = 43.33.

Missing value from average

If the average of 5 people is 20, and one has 30. Find the average of the other 4.

Sum = 5×20 = 100.

Remaining sum = 100 – 30 = 70.

New average = 70 ÷ 4 = 17.5.

ALSO READ: How to Score Maximum Marks in Cloze Test & Ratio & Proportion Concepts and Shortcuts for RBI Grade B Exam

5 Tricks to Score Fast

Here are some smart ways to solve average questions quickly in RBI Grade B Phase 1. Each trick has an example so you can see it in action.

1. Use formula in reverse to find total fast

Formula: Total = Average × Number of items.
Instead of adding all numbers, reverse the formula. Multiply the average by the number of items.

Example: Average score of 12 students = 45.

Total marks = 45 × 12 = 540. Done in 2 seconds.

2. For group averages, add weighted sums

When two or more groups are given, find the total marks of each group. Then add them. Divide by the total number of items.

Example: Class A has 20 students, avg = 60. Class B has 25 students, avg = 70.
Total A = 20 × 60 = 1200. Total B = 25 × 70 = 1750.
Combined total = 2950. Total students = 45.
Combined avg = 2950 ÷ 45 = 65.55.

3. Remove one value and recalculate

If you know the total and remove one number, just subtract it from the sum and divide again.

Example: Average of 5 matches = 50 runs. Total = 250.
One match score = 40. New total = 250 – 40 = 210.
New avg = 210 ÷ 4 = 52.5.

4. Compare two averages using ratio logic

Sometimes you don’t need full calculation. You can compare averages using ratios. This saves time.

Example: Average age of Group A = 20, Group B = 30. Number of people = 2:3.
Overall avg = (20×2 + 30×3) ÷ (2+3) = (40 + 90) ÷ 5 = 26.
Here, ratio method makes it easier to set up the weighted average.

5. Use approximation when values are easy, like multiples of 10

If numbers are close to round figures, round them up or down for faster calculation. Then adjust.

Example: Find average of 49, 51, 52, 48, 50.
Round all to 50. Sum = 50×5 = 250.
Check adjustments: +(-1) + (+1) + (+2) + (-2) + 0 = 0.
Total still = 250. Average = 250 ÷ 5 = 50.

These tricks are easy to learn. They save precious seconds in the exam. Practice them daily until they become automatic. Once you get used to spotting the right trick, average questions become your fastest source of marks.

Practice Examples

Example 1: Missing number

Five numbers have a total average of 24. Four numbers are 22, 27, 26, and 23. What is the fifth?

Sum = 5 × 24 = 120. Sum of four = 98. Missing = 22.

Example 2: Group average

Class A (10 students) avg = 70. Class B (15 students) avg = 80. What’s combined avg?

Total sum = 10×70 + 15×80 = 700 + 1200 = 1900. Students = 25. Avg = 1900 ÷ 25 = 76.

Example 3: Remove lowest score

Six scores average 60. Lowest score is 40. New average of remaining five?

Sum = 6×60 = 360. Remaining sum = 320. New avg = 320 ÷ 5 = 64.

Example 4: Compare with baseline

Average of 8 values = 50. Two values are 40 and 60. New average of remaining six?

Sum = 8×50 = 400. Remaining sum = 400 – (40 + 60) = 300. New avg = 300 ÷ 6 = 50.

How to Practice Well

Practice is as important as preparation. You can start slow, then write sums and formulas. Then, time yourself later. Use ≤1 minute per question. Mix missing value, group, and weighted problems. At the end, write the mistakes you committed in a note. Revise them daily.

Daily Mini Task:

Here’s the daily task for you:

1. Solve at least 5 average questions.
2. Include one group average.
3. Include one missing value type.
4. Learn one shortcut or trick.
5. Note down mistakes and revise them before you sleep.

Do this 10 days in a row. You will see a big improvement.

ALSO READ: Word Swap Tricks for RBI Grade B Phase 1 Exam

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Final Takeaway

Average is a frequent and fussy topic in RBI Grade B Quant. Once you know the formulas and shortcuts, it’s quick to solve. With a little daily practice, you can confidently solve any average question in the exam. This topic’s clarity and practice can give you those easy, reliable marks.

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