Question

A certain comet is visible on
earth once in every x years -
that is, it has a periodicity of
exactly x years. Three of the
years in which it was seen
are 1780, 1861, and 1987.
Which of these could be the
value of x?
i) 2
ii)5
iii)6
iv)9
Please explain this in a proper step by step manner pls as fast as possible

Answer 1

Answer:

A certain comet is visible on

earth once in every x years -

that is, it has a periodicity of

exactly x years. Three of the

years in which it was seen

are 1780, 1861, and 1987.

Which of these could be the

value of x?

i) 2

ii)5

iii)6

iv)9

Please explain this in a proper step by step manner pls as fast as possible

Answer 2

Answer:

9

Explanation:

First we take the difference of the given years:

1861--1780 = 81

1987--1861 = 126

Now the options given are 2,5,6,9

We have to pick a value from one for 'X'

X is the value of periodicity.

So we have the difference of the years as 81,126

Now we divide 81 by 2,5,6,9

81 is only divicible by 9

_______________________

Now we divide 126 by 2,5,6,9

126 is divicible by 9,2,6

But the common is 9 for both the values

Hence, the answer is 9

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