An inkjet printer can print 8 lines/second and can print a document in 6 minutes. How much time would an LED printer take to print the same document if it can print 7 lines/second more than the inkjet printer?

3 min 12 sec

1 minute = 60 seconds

6 minutes = 60 x 6 seconds = 360 seconds

Total lines in the document = 8 x 360

= 2880 lines,   ..(1.)

LED printer

Speed of LED printer = 8 + 7 = 15 lines/second   ..(2.)

Time taken by LED printer to print the document = (1)/(2)

⇒ \(\frac{2880}{15}\) = 192 seconds 

⇒ 192 x \(\frac{1}{60}\) = 3 minutes 12 seconds.