Question

A computer typist types a page with $20$ lines in $10$ minutes but he leaves $8\%$ margin on the left side of the page. Now he has to type $23$ pages with $40$ lines on each page which he leaves $25\%$ move margin than before. How much time is now required to type these $23$ pages.

• A. $7\frac{1}{2}$hrs
• B. $7\frac{2}{3}$hrs
• C. $23\frac{1}{2}$hrs
• D. $3\frac{2}{3}$hrs

Answer 1

Answer: (B)

$7\frac{2}{3}$hrs

$1$ page, $20$ lines, $8\%$ margin, $10$ minutes

Of those $20$ lines, $8\%$ of the total is blank margin, so the actual amount typed is $\frac{92}{100}\times 20=18.4$ lines in $10$ minutes, or about $1.8$ lines per minute.

$23$ pages, $40$ lines, $25\%$ more margin

To figure out new margin, we simply take the previous amount and add $25\%$ to it:$\frac{125}{100}\times 8=10$ percent margins.

Using this, we know that $10\%$ of each line is blank, so for $40$ lines, the amount typed is $40\times \frac{90}{100}=36$ lines. At a rate of $1.8$ lines per minute, each page will take $20$ minutes.

All $23$ pages will take $23\times 20=460$ minutes. Divide by 60 to get to hours and you get $\frac{460}{60}=7\frac{2}{3}$ hours.