Solution:
We have
Now, the difference inside the modulus signified the distance of n from on the number line. This means that when the absolute difference from a number is larger, n would be further away from that number.
Example: The absolute difference of n and 60 is less than that of the absolute difference between n and 20. Hence, n cannot be , as then it would be closer to 20 than 60, and closer on the number line would indicate lesser value of absolute difference. Thus we have the condition that
The absolute difference of n and 100 is less than that of the absolute difference between Hence, n cannot be , as then it would be closer to 20 than 100. Thus we have the condition that
The absolute difference of n and 60 is less than that of the absolute difference between Hence, n cannot be , as then it would be closer to 100 than 60. Thus we have the condition that
The number which satisfies the conditions are 61, 62, 63, 64......79. Thus, a total of 19 numbers.
Alternatively
as per the given condition :
Dividing the range of n into 4 segments. $(n < 20, 20 100)$
1) For
considering the inequality part :
No value of n satisfies this condition.
2) For
For
But for the considered range n is less than 60.
3) For
For the first part and for the second part
n takes values from 61 ................79.
A total of 19 values
4) For
No value of n in the given range satisfies the given inequality.
Hence a total of 19 values satisfy the inequality.
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