Logical Reasoning - Number Series - Discussion
Discussion Forum : Number Series - Type 2 (Q.No. 7)
Directions to Solve
Look carefully for the pattern, and then choose which pair of numbers comes next.
7.
17 17 34 20 20 31 23
Answer: Option
Explanation:
This is an alternating subtraction series with repetition. There are two different patterns here. In the first, a number repeats itself; then 3 is added to that number to arrive at the next number, which also repeats. This gives the series 17, 17, 20, 20, 23, and so on. Every third number follows a second pattern, in which 3 is subtracted from each number to arrive at the next: 34, 31, 28.
Discussion:
33 comments Page 3 of 4.
Deena V said:
1 decade ago
17-17= 0
17-34= -17
34-20= +14
20-20= 0
20-31= -11
31-23= +8
23-(x)= 0(i.e x =23)
23-(x)= -5(i.e x=28),
After zero, 3 is continuously subtract and polarity has been changed at this series
17-34= -17
34-20= +14
20-20= 0
20-31= -11
31-23= +8
23-(x)= 0(i.e x =23)
23-(x)= -5(i.e x=28),
After zero, 3 is continuously subtract and polarity has been changed at this series
Rajib Das said:
1 decade ago
17, 17, 34, 20, 20, 31, 23, .....What number should be next?
____a1____ _b1_ ____a2___ _b2_ ____a3___ _b3_
17 17 34 20 20 31 23 (23*?) (28*?)
0 0 0
a1=17-17=0 and a1-a2=17-20=-3
b1=20-20=0 and a2-a3=20-23=-3
So, a3=0=23-23*
Again, b1-b2=34-31=+3
So, b2-b3=+3=31-28* Ans:Next numbers are 23,28.
____a1____ _b1_ ____a2___ _b2_ ____a3___ _b3_
17 17 34 20 20 31 23 (23*?) (28*?)
0 0 0
a1=17-17=0 and a1-a2=17-20=-3
b1=20-20=0 and a2-a3=20-23=-3
So, a3=0=23-23*
Again, b1-b2=34-31=+3
So, b2-b3=+3=31-28* Ans:Next numbers are 23,28.
Saurabh said:
1 decade ago
17
17+17=34 nothing is subtracted here
20
20+20=40, 9 is subtracted here =31
23
23+23=46,18 is subtracted here = 28
so option e is correct
17+17=34 nothing is subtracted here
20
20+20=40, 9 is subtracted here =31
23
23+23=46,18 is subtracted here = 28
so option e is correct
(1)
Shreshth said:
1 decade ago
Nice Priyanka....
(1)
Priyanka said:
1 decade ago
Ohhhhho very simple Technique : Take two series like as:
1st series: 17,17....20,20.... nw 23,23..... that means add +3
2nd series: 34....... 31.... now 28... that means subtract -3
Simple combination of two series....
So ans will be 23,28.
1st series: 17,17....20,20.... nw 23,23..... that means add +3
2nd series: 34....... 31.... now 28... that means subtract -3
Simple combination of two series....
So ans will be 23,28.
(1)
Vamsimohan said:
1 decade ago
@Rajanna nice explanation..
(1)
Keerthi said:
1 decade ago
17+3=20 20+3=23 17,20,23 add +3
34-3=31 31-3=28 34,31,28 are sub -3
34-3=31 31-3=28 34,31,28 are sub -3
(1)
Rajanna said:
1 decade ago
First of three nos 17 17 34
second 20 20 31
Third of three 23 23 28
sol: 17 +3 17+3 34-3 so on..........
second 20 20 31
Third of three 23 23 28
sol: 17 +3 17+3 34-3 so on..........
Komal said:
1 decade ago
17 17 Series 1
34 is Series 2
We have to add 3 in series 1 i.e 17+3=20
After this we have to subtract 3 from Series 2 i.e 34-3=31
Then answer is 20+3=23 and 31-3= 28
Answer is 23 28
34 is Series 2
We have to add 3 in series 1 i.e 17+3=20
After this we have to subtract 3 from Series 2 i.e 34-3=31
Then answer is 20+3=23 and 31-3= 28
Answer is 23 28
Poonam said:
1 decade ago
Can you explain in easy way.
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