Mixing
Approximating values while calculating percentage changes
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At times, in certain types of data interpretation questions that usually get asked in aptitude examinations, some techniques are employed to cut time on calculation and get a near perfect answer. One such technique is used in my book. Please find its screenshot below.
Please read the Application 2 part of the page. PCG stands for percentage change graphic. It's just a fancy name used by the author for the particular arrow diagram he uses to show percentage change. Now read the part marked with red ink. This part is not clear. Also, the author has written that he has elaborated more on it in 'Ratio and Proportions' chapter but there is not even a mention of this in that particular chapter.
Could anyone please explain clearly how such approximations are used?
arithmetic approximation percentages mental-arithmetic
asked Jan 26 at 18:19
Aamir KhanAamir Khan
455
$endgroup$
add a comment |
$begingroup$
At times, in certain types of data interpretation questions that usually get asked in aptitude examinations, some techniques are employed to cut time on calculation and get a near perfect answer. One such technique is used in my book. Please find its screenshot below.
Please read the Application 2 part of the page. PCG stands for percentage change graphic. It's just a fancy name used by the author for the particular arrow diagram he uses to show percentage change. Now read the part marked with red ink. This part is not clear. Also, the author has written that he has elaborated more on it in 'Ratio and Proportions' chapter but there is not even a mention of this in that particular chapter.
Could anyone please explain clearly how such approximations are used?
arithmetic approximation percentages mental-arithmetic
asked Jan 26 at 18:19
Aamir KhanAamir Khan
455
$endgroup$
$begingroup$
Presumably the argument is that errors from rounding do not grow quickly. To take an example of the possible scale of the issue, $300.4999 times 300.4999 approx 90300$ while to three significant figures $300 times 300 = 90000$, so a difference of just $3$ in the third significant place of the product, and most other examples will be less extreme than this
$endgroup$
– Henry
Jan 26 at 18:48
add a comment |
$begingroup$
At times, in certain types of data interpretation questions that usually get asked in aptitude examinations, some techniques are employed to cut time on calculation and get a near perfect answer. One such technique is used in my book. Please find its screenshot below.
Please read the Application 2 part of the page. PCG stands for percentage change graphic. It's just a fancy name used by the author for the particular arrow diagram he uses to show percentage change. Now read the part marked with red ink. This part is not clear. Also, the author has written that he has elaborated more on it in 'Ratio and Proportions' chapter but there is not even a mention of this in that particular chapter.
Could anyone please explain clearly how such approximations are used?
arithmetic approximation percentages mental-arithmetic
asked Jan 26 at 18:19
Aamir KhanAamir Khan
455
$endgroup$
At times, in certain types of data interpretation questions that usually get asked in aptitude examinations, some techniques are employed to cut time on calculation and get a near perfect answer. One such technique is used in my book. Please find its screenshot below.
Please read the Application 2 part of the page. PCG stands for percentage change graphic. It's just a fancy name used by the author for the particular arrow diagram he uses to show percentage change. Now read the part marked with red ink. This part is not clear. Also, the author has written that he has elaborated more on it in 'Ratio and Proportions' chapter but there is not even a mention of this in that particular chapter.
Could anyone please explain clearly how such approximations are used?
arithmetic approximation percentages mental-arithmetic
arithmetic approximation percentages mental-arithmetic
asked Jan 26 at 18:19
Aamir KhanAamir Khan
455
asked Jan 26 at 18:19
Aamir KhanAamir Khan
455
edited Jan 26 at 18:47
Aamir Khan
asked Jan 26 at 18:19
Aamir KhanAamir Khan
455
asked Jan 26 at 18:19
Aamir KhanAamir Khan
455
asked Jan 26 at 18:19
Aamir KhanAamir Khan
455
455
$begingroup$
Presumably the argument is that errors from rounding do not grow quickly. To take an example of the possible scale of the issue, $300.4999 times 300.4999 approx 90300$ while to three significant figures $300 times 300 = 90000$, so a difference of just $3$ in the third significant place of the product, and most other examples will be less extreme than this
$endgroup$
– Henry
Jan 26 at 18:48
add a comment |
$begingroup$
Presumably the argument is that errors from rounding do not grow quickly. To take an example of the possible scale of the issue, $300.4999 times 300.4999 approx 90300$ while to three significant figures $300 times 300 = 90000$, so a difference of just $3$ in the third significant place of the product, and most other examples will be less extreme than this
$endgroup$
– Henry
Jan 26 at 18:48
$begingroup$
Presumably the argument is that errors from rounding do not grow quickly. To take an example of the possible scale of the issue, $300.4999 times 300.4999 approx 90300$ while to three significant figures $300 times 300 = 90000$, so a difference of just $3$ in the third significant place of the product, and most other examples will be less extreme than this
$endgroup$
– Henry
Jan 26 at 18:48
$begingroup$
Presumably the argument is that errors from rounding do not grow quickly. To take an example of the possible scale of the issue, $300.4999 times 300.4999 approx 90300$ while to three significant figures $300 times 300 = 90000$, so a difference of just $3$ in the third significant place of the product, and most other examples will be less extreme than this
$endgroup$
– Henry
Jan 26 at 18:48
add a comment |
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$begingroup$
Presumably the argument is that errors from rounding do not grow quickly. To take an example of the possible scale of the issue, $300.4999 times 300.4999 approx 90300$ while to three significant figures $300 times 300 = 90000$, so a difference of just $3$ in the third significant place of the product, and most other examples will be less extreme than this
$endgroup$
– Henry
Jan 26 at 18:48