Nitin was counting down from 31. Sumit was counting upwards the numbers starting from 1
and he was calling out only the odd numbers. What common number will they call out at the
same time if they were calling out at the same speed ?
(A) 19
(B) 21
(C) 22
(D) They will not call out the same number
Answers
Given : Nitin was counting down from 31.
Sumit was counting upwards from 1 and was calling out only odd numbers
To Find : common number they call out at the same time
(a) 19
(b) 21
(c) 22
D) They will not call out the same number
Solution:
1st called
31 and 1
Difference = 30
Now Nitin called = 31 - 1 = 30
and Sumit called = 1 + 2 = 3
Difference = 27
on 1st calling Difference = 30
on 2nd calling difference = 27
on 3rd calling difference = 24 and so on
0 = 30 + (n - 1)(-3)
=> n = 11
11th Calling
on 1st calling number was 31
31 + (11 - 1)(-1) = 31 - 10 = 21
on 11 th calling number = 21
or 1 + (11 - 1)*2 = 21
Hence common number called = 21 at same time
31 1
30 3
29 5
28 7
27 9
26 11
25 13
24 15
23 17
22 19
21 21
common number called = 21 at same time
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Answer:
common number called =21 at same time