November 14th, 2018, 11:29 AM  #1 
Member Joined: Aug 2018 From: Nigeria Posts: 73 Thanks: 2  Help on these, found it to be very tough...
1. The ratio of girls to boys is 5:6. On a rainy day, 1/6 of girls and 1/4 of boys were absent. If the total number of pupils present was 390, how many of the pupils were boys? 2. Two cars X and Y start at the same point and travel toward point P which is 150km away. If the average speed of Y is 60km/h and X arrives at P 25 minutes earlier, what is the average speed of X? 3. A & B can do a piece of work in 15 days. They both started, but after 6 days B gets ill and A takes 30 more days to finish the job himself. How long would each take working alone? Last edited by skipjack; November 15th, 2018 at 02:53 AM. 
November 14th, 2018, 12:28 PM  #2 
Math Team Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 14,580 Thanks: 1038 
Would be easier to "help" if you posted only ONE problem per thread.

November 14th, 2018, 12:38 PM  #3 
Member Joined: Aug 2018 From: Nigeria Posts: 73 Thanks: 2 
Sorry as I need the solution to those urgently

November 14th, 2018, 12:45 PM  #4 
Senior Member Joined: Feb 2016 From: Australia Posts: 1,821 Thanks: 643 Math Focus: Yet to find out.  
November 14th, 2018, 02:00 PM  #5 
Senior Member Joined: Feb 2016 From: Australia Posts: 1,821 Thanks: 643 Math Focus: Yet to find out. 
What always baffles me is that more time is spent trying to obtain a "quick answer" than actually just showing some scratch work/your thoughts on the problem.. Do you understand what I mean by this Harmeed? 
November 14th, 2018, 02:52 PM  #6 
Math Team Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 14,580 Thanks: 1038  
November 14th, 2018, 03:21 PM  #7  
Math Team Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 14,580 Thanks: 1038  Quote:
b = boys, g = girls g/b = 5/6 : b = 6g/5 5g/6 + 3b/4 = 390 Last edited by skipjack; November 15th, 2018 at 02:54 AM.  
November 14th, 2018, 07:19 PM  #8 
Member Joined: Aug 2018 From: Nigeria Posts: 73 Thanks: 2 
Thanks for the hint... Was of the rest?

November 14th, 2018, 08:13 PM  #9 
Member Joined: Aug 2018 From: Nigeria Posts: 73 Thanks: 2 
I obtained 240

November 15th, 2018, 02:55 AM  #10 
Global Moderator Joined: Dec 2006 Posts: 20,746 Thanks: 2133 
Are you sure the numbers of pupils are correct? For every 30 girls and 36 boys, 25 girls and 27 boys attended, so the number of pupils who attended must be a multiple of 52, such as 364 or 416, not 390. Last edited by skipjack; November 15th, 2018 at 12:50 PM. 

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