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Family Average

Family Average problems involve calculating or using the average age of family members. These problems test your understanding of the relationship between sum, average, and number of members.

10Worksheets
200+Practice Questions
BeginnerDifficulty
1-2 hoursHours to Master

What You'll Learn

Introduction & Overview Why This Matters How to Solve Pro Tips & Tricks
Shortcut Methods Common Mistakes Practice Worksheets Exam Importance

Introduction to Family Average

Family Average problems involve calculating or using the average age of family members. These problems test your understanding of the relationship between sum, average, and number of members.

Prerequisites

Average formula Sum = Average × Number Basic arithmetic
Why This Matters: Family Average problems appear in 1-2 questions in banking and SSC exams. They test average concepts in a family context.

How to Solve Family Average Problems

1

Step 1: Use the formula: Sum of ages = Average × Number of members

2

Step 2: Calculate the total sum from given average

3

Step 3: For future averages, add n years to each person's age

4

Step 4: New total sum = Old sum + (n × number_of_members)

5

Step 5: New average = New sum ÷ Number of members

6

Step 6: For past averages, subtract instead of add

7

Step 7: Answer the specific question asked

Pro Strategy: Remember that when all members age equally, the average increases by exactly the same number of years.

Example Problem

Example: Average age of a family of 4 members is 30 years. What will be the average age after 5 years? Solution: Step 1: Present total sum = 30 × 4 = 120 years Step 2: After 5 years, each of 4 members ages 5 years Step 3: New total sum = 120 + (5 × 4) = 120 + 20 = 140 years Step 4: New average = 140 ÷ 4 = 35 years Answer: 35 years Shortcut: New average = 30 + 5 = 35 years

Pro Tips & Tricks

  • New average = Old average + n (when no members change)
  • Total sum = Average × Count
  • When a member leaves, subtract their age from total sum
  • When a member joins, add their age to total sum
  • Average n years ago = Present average - n
  • The sum increases by (n × number of persons) over n years

Shortcut Methods to Solve Faster

Average after n years = Present average + n
Average n years ago = Present average - n
Total sum = Average × Count

Common Mistakes to Avoid

Adding n to average without multiplying by count for total sum
Forgetting to update the count when members change
Using average instead of sum in replacement problems
Confusing sum with average in formulas

Exam Importance

Family Average is an important topic for various competitive exams. Here's how frequently it appears:

SSC CGL
1-2 questions
BANKING PO
1-2 questions
RAILWAYS RRB
1-2 questions
CAT
0-1 questions
INSURANCE
1-2 questions

Ready to Master Family Average?

Start with Worksheet 1 and work your way up to expert level! Each worksheet includes:

20 practice questions
Detailed solutions
Step-by-step explanations
Start Practicing Now