CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
The average of four numbers is 18. If one number is increased by 8, what is the new average?
A. 19
B. 18
C. 20
D. 22
Correct Answer: C
Total increases by 8, so average increases by 8/4=2.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
The average of a, b and c is 15. If a+b=20, find c.
A. 30
B. 25
C. 20
D. 15
Correct Answer: B
Total=3×15=45. Therefore c=45−20=25.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
The average of x and y is 20. If x=26, find y.
A. 14
B. 20
C. 16
D. 12
Correct Answer: A
x+y=40. Thus y=40−26=14.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
A car travels for equal times at 60 km/h and 40 km/h. What is its average speed?
A. 50
B. 48
C. 55
D. 52
Correct Answer: A
For equal times, average speed is arithmetic mean=(60+40)/2=50.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
A car covers equal distances at 60 km/h and 40 km/h. What is its average speed?
A. 48
B. 52
C. 50
D. 45
Correct Answer: A
For equal distances, average speed=2ab/(a+b)=2×60×40/100=48.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
Three kilograms of an item cost Rs. 200 per kg and two kilograms cost Rs. 250 per kg. What is the average cost per kg?
A. 230
B. 220
C. 210
D. 225
Correct Answer: B
Weighted average=(3×200+2×250)/5=1100/5=220.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
A group of 40 students has an average of 55 and another group of 60 has an average of 65. What is the combined average?
A. 61
B. 60
C. 62
D. 59
Correct Answer: A
Combined average=(40×55+60×65)/100=6100/100=61.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
The average salary of 10 workers is Rs. 25,000. A manager earning Rs. 50,000 is included. What is the new average salary (approximately)?
A. Rs. 30,000
B. Rs. 27,273
C. Rs. 28,000
D. Rs. 26,500
Correct Answer: B
New total=250,000+50,000=300,000. Divide by 11 to get approximately Rs. 27,273.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
The average temperature for seven days is 30°C. The average for the first six days is 29°C. What is the seventh day's temperature?
A. 35
B. 36
C. 34
D. 30
Correct Answer: B
Seven-day total=210; first six total=174; seventh=36.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
The average of nine numbers was calculated as 24, but 32 was used instead of 23. What is the correct average?
A. 22
B. 23
C. 24
D. 25
Correct Answer: B
Wrong total=216. Correct total=216−32+23=207; average=207/9=23.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
The average of 12 numbers is 30. The average of the first seven is 28. What is the average of the last five?
A. 32.8
B. 33
C. 32
D. 31.2
Correct Answer: A
Total=360; first seven total=196; last five total=164; average=164/5=32.8.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
A class has equal numbers of boys and girls. Boys average 40 marks and girls average 50 marks. What is the class average?
A. 44
B. 42
C. 45
D. 46
Correct Answer: C
With equal group sizes, combined average is the simple mean: (40+50)/2=45.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
A batsman has 1200 runs after 25 innings. He scores 100 in the 26th inning. What is his new average?
A. 49
B. 52
C. 50
D. 48
Correct Answer: C
New total=1300; average=1300/26=50.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
A batsman has an average of 48 runs after 25 innings. How many runs has he scored?
A. 1200
B. 1150
C. 1300
D. 1250
Correct Answer: A
Total runs=48×25=1200.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
A student averages 72 marks in five subjects and scores 84 in the sixth. What is the new average?
A. 74
B. 76
C. 72
D. 73
Correct Answer: A
First five total=360; new total=444; average=444/6=74.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
If every value in a data set is multiplied by 3, how does the average change?
A. It remains unchanged
B. It becomes three times
C. It increases by 3
D. It is divided by 3
Correct Answer: B
Multiplying every observation by 3 multiplies the mean by 3.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
The average of 10 numbers is 45. If each number is increased by 5, what is the new average?
A. 45
B. 49
C. 50
D. 55
Correct Answer: C
Adding 5 to every observation adds 5 to the average.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
What is the average of the first 20 odd natural numbers?
A. 21
B. 40
C. 19
D. 20
Correct Answer: D
The average of the first n odd numbers is n; for n=20, it is 20.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
What is the average of the first 10 natural numbers?
A. 5
B. 10
C. 6
D. 5.5
Correct Answer: D
Average of 1 to n=(n+1)/2. For n=10, average=5.5.
CSS - PMS - CCE - PCS - Mathematics
Average / Arithmetic Mean
Six consecutive even integers have an average of 21. What is the smallest integer?
A. 20
B. 18
C. 16
D. 14
Correct Answer: C
The six integers are 16,18,20,22,24,26, whose average is 21.