in a town there are 1600 phones out of which 3/4 are dial phones 1/3 of those dial phones are replaced by touch-tone phones and 300 additional touch tone phones are installed. the fraction representing the touch tone phones in town is:

Question

in a town there are 1600 phones out of which 3/4 are dial phones 1/3 of those dial phones are replaced by touch-tone phones and 300 additional touch tone phones are installed. the fraction representing the touch tone phones in town is:
(a) 7/19 (b) 11/19

Henry · Accepted Answer

3/4 * 1600 = 1200 Dial phones. 1/3 * 1200 = 400 Replaced by touch-tones. 400 + 300 = 700 = Total touch-tone phones. 700/(1600+300) = 700/1900 = 7/19 = a.