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Statistics- Class 10 MCQ Test 1

Question 1. If the mean of numbers (27+x),(31+x),(89+x),(107+x),(156+x) is 82, then the mean of (130+x),(126+x),(68+x),(50+x),(1+x) is
A)100
B)75
C)85
D)66
Answer: B
Explanation:
Mean of numbers (27+x),(31+x),(89+x),(107+x),(156+x) = 82
=> (27+x)+(31+x)+(89+x)+(107+x)+(156+x) = 82*5
=> 27+31+89+107+156+5x = 410
=> 5x = 410-410
=> x = 0
therefore, mean of (130+x),(126+x),(68+x),(50+x),(1+x)
=>[(130+x)+(126+x)+(68+x)+(50+x)+(1+x)]/5
=>[130+126+68+50+1]/5 =75
Question 2. The mean of three numbers is 10. The mean of other four numbers is 12. Find the mean of all the numbers.
Answer : B
Explanation:
Mean of three numbers = 10
=> Sum of three numbers = 10*3=30
Mean of other four numbers = 12
=> Sum of other four numbers = 12*4=48
therefore, Sum of other four numbers=30+48=78
=>Mean of all seven numbers = 78/7
=>11.15
Question 3.Find x if the mean of the numbers 10,4,1,15,15,x,12 and 14 is 10
A)6
B)7
C)8
D)9
Answer : D
Explanation:
mean of the numbers 10,4,1,15,15,x,12 and 14 = 10
=> Sum of the numbers 10,4,1,15,15,x,12 and 14= 10*8=80
=> 10+4+1+15+15+x+12+14= 10*8=80
=> 71+x= 80
=> x= 80-71=9
Question 4.The mean of 9 numbers is 10. If one more number is added, the mean remains as 10. Find the number which is added.
A)0
B)9
C)8
D)10
Answer: D
Explanation:

Explanation:
Mean of 9 numbers = 10
=> Sum of 9 numbers= 10*9 = 90
Let one number equal to x is added.
=> Sum of 10 numbers= 90+x
=> mean of 10 numbers= 10
=> (90+x)/10=10
=> 90+x=90
=> x=0
Question 5. The mean of 15 numbers is 27. If each number is multiplied by 4, what will be the mean of the new numbers?
A)100
B)103
C)108
D)111
Answer: C
Question 6. Find the mean of 20 numbers such that if the mean of 8 of them is 10 and the mean of 10 of them is 12 the last two numbers are 8 and 12
A)10
B)11
C)12
D)13
Answer: B
Question 7. If the mean of 4 numbers, 2,6,7 and a is 15 and also the mean of other 5 numbers, 6, 18, 1, a, b is 50. What is the value of b?
A)42
B)130
C)180
D)45
Answer: C
Question 8. The mean of five numbers is 28. If one of the numbers is excluded, the mean gets reduced by 2. The excluded number is -------.




Answer: A
Question 9. The mean weight of 8 numbers is 15. If each number is added by 2, what will be the new mean?




Answer: A
Question 10. Mean of 100 items is 49. It was discovered that three items which should have been 60, 70, 80 were wrongly read as 40, 20, 50 respectively. The correct mean is




Answer: C

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