Practice Questions
Concept Explanation
When two or more groups are merged, the combined average is:
Combined average = (n₁×A₁ + n₂×A₂) / (n₁ + n₂)
Key Idea
- Find total sum of each group, add them, divide by total count.
- The larger group pulls the combined average toward its own average.
Example
Group 1: 30 students, avg 40. Group 2: 20 students, avg 55. Combined = (1200 + 1100)/50 = 46.
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Q1 Easy
Group 1: 30 students, average 40. Group 2: 20 students, average 55. Combined average is:
Explanation(1200 + 1100)/50 = 46. -
Q2 Medium
Section A: 25 students, average 60. Section B: 35 students, average 70. Combined average is:
Explanation(1500 + 2450)/60 = 65.83 (approx). -
Q3 Medium
Three groups: 10 avg 20, 15 avg 30, 25 avg 40. Combined average is:
Explanation(200 + 450 + 1000)/50 = 33. -
Q4 Medium
Class X: 40 students, average 72. Class Y: 60 students, average 78. Combined average is:
Explanation(2880 + 4680)/100 = 75.6. -
Q5 Easy
Boys: 20, average height 160 cm. Girls: 30, average 165 cm. Combined average height is:
Explanation(3200 + 4950)/50 = 163 cm. -
Q6 Easy
Two equal groups have averages 50 and 60. Combined average is:
ExplanationEqual groups: average of the two averages = 55. -
Q7 Medium
Dept A: 15 employees, avg salary Rs. 48,000. Dept B: 25 employees, avg Rs. 52,000. Combined average salary is:
Explanation(720000 + 1300000)/40 = Rs. 50,500.
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Q8 Medium
Team P: 12 members, average 35. Team Q: 18 members, average 45. Combined average is:
Explanation(420 + 810)/30 = 41. -
Q9 Easy
Batch 1: 50 students, average 65. Batch 2: 50 students, average 75. Combined average is:
Explanation(3250 + 3750)/100 = 70. -
Q10 Medium
Factory A: 8 workers, avg output 120. Factory B: 12 workers, avg 150. Combined average output is:
Explanation(960 + 1800)/20 = 138. -
Q11 Hard
In a company, 100 employees avg Rs. 30,000 and 200 employees avg Rs. 36,000. Overall average salary is:
Explanation(3000000 + 7200000)/300 = Rs. 34,000. -
Q12 Medium
Group of 10 avg 25 and group of 40 avg 40. Combined average is:
Explanation(250 + 1600)/50 = 37. -
Q13 Medium
Two classes: 30 avg 55, 50 avg 65. Combined average is:
Explanation(1650 + 3250)/80 = 61.25. -
Q14 Easy
If n₁ = n₂, combined average of A₁ and A₂ equals:
ExplanationEqual-sized groups give the arithmetic mean of the two averages.
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DS1 Easy
What is the combined average?
Statement IGroup 1: 30 students, average 40.
Statement IIGroup 2: 20 students, average 55.
ExplanationNeed both groups. Combined average = 46. -
DS2 Medium
What is the combined average of two equal-sized groups?
Statement IThe first group average is 48.
Statement IIThe second group average is 52.
ExplanationNeed both group averages. Combined = (48 + 52)/2 = 50.
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DS3 Medium
Is the combined average closer to the larger group's average?
Statement IGroup 1 has 10 members, average 20.
Statement IIGroup 2 has 90 members, average 50.
ExplanationTogether: combined = (200 + 4500)/100 = 47, closer to 50. -
DS4 Easy
What is the combined average of two equal groups?
Statement IFirst group average is 48.
Statement IISecond group average is 52.
ExplanationNeed both averages. Combined = (48 + 52)/2 = 50.