IMO Mathematics Olympiad Class 8: Questions 570  576 of 1029
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Question number: 570
» Direct and Inverse Proportions
Question
If 4 men take an hour to dig a ditch, how long should it take 10 men to dig a ditch of the same type?
Choices
Choice (4)  Response  

a.  20 min 

b.  23 min 

c.  24 min 

d.  30 min 

Question number: 571
Question
Number of prime factors in is
Choices
Choice (4)  Response  

a.  20 

b.  28 

c.  23 

d.  22 

Question number: 572
» Direct and Inverse Proportions
Question
If A: B = 3: 4 and B: C = 5: 6, then C: A is equal to, ________.
Choices
Choice (4)  Response  

a.  15: 14 

b.  24: 15 

c.  12: 23 

d.  25: 14 

Question number: 573
Question
The value of when is________.
Choices
Choice (4)  Response  

a.  80 

b.  81 

c.  85 

d.  84 

Question number: 574
» Direct and Inverse Proportions
Question
A cistern has two inlets A and B which can fill it in 10 minutes and 20 minutes respectively. An outlet C can empty the full cistern in 4 minutes. If all the pipes are opened together in the empty tank, time taken to fill the tank completely is ________.
Choices
Choice (4)  Response  

a.  25 minutes 

b.  20 minutes 

c.  15 minutes 

d.  10 minutes 

Question number: 575
Question
Number of prime factors in is
Choices
Choice (4)  Response  

a.  73 

b.  60 

c.  66 

d.  70 

Question number: 576
» Direct and Inverse Proportions
Question
A water tank is twofifth full. Pipe A can fill a tank in 12 minutes and pipe B can empty it in 6 minutes. If both the pipes are open, how long will it take to empty or fill the tank completely?
Choices
Choice (4)  Response  

a.  4.8 minutes 

b.  5 minutes 

c.  4 minutes 

d.  5.5 minutes 
