1. The average of 7, 11, 15, x, 14, 21, 25 is 15, then the value of x is:
7, 11, 15, x, 14, 21, 25 का औसत 15 है तो का मान ज्ञात करें।
Option (A). 3
Option (B). 12.5
Option (C). 12
Option (D). 13.5
Answer
Option (C) 12.
Solution:-
15 = (7+11+15+X+14+21+25)/7
105 = 93 + X
X = 12
Answer.
2 A student was asked to find the value of x, and given the arithmetic mean is 12 of the following 12 numbers:
3, 11, 7, 9, 15, 13, 8, 19, 17, 21, 14 and X
एक विद्यार्थी से x का मान ज्ञात करने को कहा गया यदि दिए गए संख्याओं 3, 11, 7, 9, 15, 13, 8, 19, 17, 21, 14 एवं x का समान्तर माध्य 12 है।
Option (A). 5
Option (B). 7
Option (C). 8
Option (D). 11
Answer:-
Option (B) 7
Solution:-
12 = (3+ 11+ 7+ 9+ 15+ 13+ 8+ 19+ 17+ 21+ 14+ X)/ 12
12×12 = 137 + X
X = 144 - 137
X = 7
Answer
प्रथम 100 धनात्मक संख्याओं का औसत ज्ञात करें।
Option (A). 100
Option (B). 51
Option (C). 50.5
Option (D). 49.5
Answer:-
Option (C) 50.5
Solution:-
1+ 2+ 3+ .................. +100
Average = (First term + Last term)/2
= (1+100)/2
= 101/2
= 50.5
Answer
4. The average of odd numbers upto 100 is:
100 तक की सभी विषम संख्याओं का औसत ज्ञात करें।
Option (A). 51
Option (B). 50
Option (C). 49
Option (D). 52
Answer:-
Option (B) 50
Solution
1+ 3+ 5+ 7+ .............+99
Average = (First term + Last term)/2
= (1 + 99)/2
= 100/2
= 50
5. The average of even numbers upto 100 is:
100 तक की सभी सम संख्याओं का औसत ज्ञात करें।
Option (A). 49
Option (B). 48
Option (C). 50
Option (D). 51
Answer:-
Option (D) 51
Solution
2+ 4+ 6+ 8+ .............+100
Average = (First term + Last term)/2
= (2 + 100)/2
= 102/2
= 51
6. The average of the squares of first ten natural numbers:-
प्रथम 10 संख्याओं के वर्ग का औसत ज्ञात करें।
Option (A). 35.5
Option (B). 36.5
Option (C). 37.5
Option (D). 38.5
Answer:-
Option (D) 38.5
Solution
Average of Square of first n Natural Number
= [n(n+1) (2n+ 1)]/ 6n
= [n(n+ 1) (2n+ 1)] 6
Average of Square of first 10 Natural Number
= [(10+ 1) (20+ 1)]/6
= (11 × 21)/6
= 38.5
7. What is the average of the cubes of first nine natural numbers?
प्रथम 9 संख्याओं के घन का औसत ज्ञात करें?
Option (A). 220
Option (B). 320
Option (C). 325
Option (D). 225
Answer:-
Option (D) 255
The average of the cubes of first n natural numbers
= n(n+ 1)²/4
= 9(10)²/4
= (9× 100) / 4
= 225
