Correct Answer - Option 1 : 231.67
option (1)
CONCEPT:
- The rule for Significant figures in Addition and Subtraction:
- The final result should retain as many decimal places as there in the original number with the least decimal places.
- Count the number of significant figures in the decimal portion.
- It should retain as many decimal places as there in the original number with the least decimal places.
- The final answer has no more significant figures to the right of the decimal.
- We have to count the least number of significant figures in any number in the problem.
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Rounding off the digits: The rules employed for rounding off a number to is given below,
- If the digit to be is more than 5, the digit to increased by one.
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for example:
-
2.488 If we have to remove 8, we have to round it to 2.49
- Because the digit is more than 5, so it will increase by 1
- Hence it will be round it to 2.49
- If the digit is less than 5, then the preceding number will not be changed.
EXPLANATION:
- In addition and subtraction
- The answer should be reported to the same number of decimal places as the number with the least decimal places.
- On adding this expression using scientific notation
23.44 + 208.226 = 231.666
- The answer we have to take according to the rule,
- We have to count the least number of significant figures in any number in the problem.
- So as per the question, in 23.44 and 208.226 we can see 2 is the minimum no. with the least decimal places.
- Hence we have to round off the answer as 2 significant figures.
The final answer will be: 231.67
- Following example for better understanding:
- In 5.334 if 4 is to be removed, as we can see 4 is less than 5 then the result is rounded up to 5.33
- If the rightmost digit to be removed is 5, then the increasing number is not changed
- If the number will be even so it is increased by one
- if it is an odd number then we have to round off the digit
- For example,
- if 7.75 is to be rounded by removing 5,
- we have to increase 7 to 8 giving 7.8 as the result.
- However, if 7.26 is to be rounded off it is rounded off to 7.2 because 2 is an even number.
