M4maths Previous Puzzles

17 Jun 2022 Average

The average of 14 number is 47. The average of the last five numbers is 50 and that of first six numbers is 44. The ninth number is 3 less than the seventh number but 6 more than the eighth number. The average of eighth and ninth number is:

OPtion

1) 47.5
2) 50.5
3) 51.5
4) 48.5
5) 48
6) 51
7) 46
8) 49
9) 45
10) None of these

Solution

Total of 14 numbers = 14*47 = 658
Total of 7th, 8th, 9th number = 658 - Total of last five numbers - Total of first six numbers = 658 - 5*50 - 6*44 = 144
Let the 9th number=x, then 7th number=x+3 and 8th number=x-6
.'. Sum of 7th, 8th & 9th number = x+(x+3)+(x-6) = 144
⇒ 3x - 3=144 or x=49
Hence average of 8th & 9th number = [(x-6)+x]/2 = (43+49)/2 = 46
Correct Option 7)

Correct Option: 7 Best Solution (2)

G.S.Kantharao   2 years AGO

Average of 14=47
Total=658
Average of 5=50
Average of 6=44
Sum of 11=250+264=514
7,8,9 terms=x+3,x-6,x
So 3x-3=658-514=144=>x=49
Average
=x-6+x/2=x-3=49-3=46
My option is 7👈

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RAMADURAI NATESAN   2 years AGO

A = N1 + ......+ N6 = 264. B = N10 + .....+N14 = 250. A + B = 514
N7 = N8+9 = N9 +3 . N7 +N8 +N9 = 658 - 514 = 144..3N7 =156.
N7 = 52. N8 + N9= 92. AVG. OF N8,N9 = 46

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