Practice Questions
Concept Explanation
Marks problems use standard average formulas. Common patterns include finding a missing score, required score for a target average, and combined class averages.
Key Formulas
- Total marks = Average × Number of subjects/tests
- Required score = (Target average × n) − Sum of known scores
- Combined class average = Total marks of all students / Total students
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Q1 Easy
A student scores 80, 85, 90, 95 and 100 in five subjects. Average marks are:
ExplanationSum = 450. Average = 450/5 = 90. -
Q2 Easy
Average of 4 tests is 75. Scores in three tests are 70, 72 and 78. Fourth test score is:
ExplanationTotal = 300. Fourth = 300 − 220 = 80. -
Q3 Medium
A student needs average 90 in 5 tests. First four averages 85. Fifth test score needed is:
ExplanationRequired total = 450. Current total = 340. Needed = 110. -
Q4 Hard
Average marks of 20 students is 65. One student's marks are excluded and new average is 64. Excluded marks are:
ExplanationOld sum = 1300. New sum = 64 × 19 = 1216. Excluded = 84. -
Q5 Medium
In a class of 30, average marks is 60. If highest 80 and lowest 40 are removed, new average of remaining 28 is:
ExplanationTotal = 1800. Remaining sum = 1800 − 120 = 1680. Average = 1680/28 = 60. -
Q6 Medium
Average of 6 subjects is 72. Marks in five subjects are 68, 70, 74, 76 and 80. Sixth subject marks are:
ExplanationTotal = 432. Sixth = 432 − 368 = 64. -
Q7 Medium
A student averages 55 in 4 tests and 65 in next 6 tests. Overall average in 10 tests is:
Explanation(220 + 390)/10 = 61.
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Q8 Medium
After 8 tests, average is 70. After 9th test, average becomes 72. Ninth test score is:
ExplanationOld sum = 560. New sum = 648. Ninth score = 88. -
Q9 Medium
Class A (25 students) average 58. Class B (35 students) average 62. Combined average is:
Explanation(1450 + 2170)/60 = 60.33 (approx). -
Q10 Easy
A student scored 45, 50, 55 in three tests. Score needed in fourth test for average 55 is:
ExplanationRequired total = 220. Current = 150. Needed = 70. -
Q11 Medium
Average marks of 15 students is 48. One paper re-evaluated from 42 to 62. New average is:
ExplanationSum increases by 20. New average = 48 + 20/15 = 49.33 (approx). -
Q12 Easy
In 5 papers of 100 marks each, a student averages 76%. Total marks scored are:
ExplanationTotal = 76 × 5 = 380 marks. -
Q13 Hard
Average of 7 numbers is 50. If 65 replaces 35, new average is:
ExplanationSum increases by 30. New average = 50 + 30/7 = 54.29 (approx). -
Q14 Medium
A student needs 80% average in 5 tests of 100 marks. Scored 75, 78, 82, 85. Minimum fifth score needed is:
ExplanationRequired total = 400. Current = 320. Minimum needed = 80.
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DS1 Easy
What is the average marks?
Statement IMarks in four tests are 70, 72, 78 and 80.
Statement IITotal marks in four tests is 300.
ExplanationEach statement alone gives average = 300/4 = 75. -
DS2 Medium
What is the fifth test score needed for average 90?
Statement IFirst four tests average 85.
Statement IIThere are 5 tests in total.
ExplanationTogether: needed total = 450, current = 340, fifth = 110.
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DS3 Easy
What is the combined class average?
Statement IClass A: 25 students, average 58.
Statement IIClass B: 35 students, average 62.
ExplanationNeed both classes. Combined average = 60.33 (approx). -
DS4 Medium
Is the student's average above 70?
Statement IThe student scored 68, 72, 74 and 76 in four tests.
Statement IITotal marks in four tests is 290.
ExplanationEach alone: average = 290/4 = 72.5 > 70.