Question

Mr.kanja,Miss Kanene and Mrs Nyaga have to mark a form three contest for 160 students.They take 5mins,4mins and 12 mins respectively to mark a script.If they all start to mark at 9:00am non-stop,what is the shortest time they can take to complete the marking.i got 60 mins bt the ans says 300.Someone help.

Answer 1

(t / 5) + (t / 4) + (t / 12) = 160

multiplying by 60 (the LCD) ... 12 t + 15 t + 5 t = 9600

32 t = 9600 ... t = ?

Answer 2

You divide the 300 by 60 to get 5hrs