IMO Mathematics Olympiad (SOF) Class 10: Questions 513  518 of 958
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Question number: 513
Question
5 bells commence tolling together and toll at intervals of 3,6, 9,12 and 15 seconds respectively. In 12 minutes, how many times do they toll together?
Choices
Choice (4)  Response  

a.  5 

b.  6 

c.  7 

d.  4 

Question number: 514
Question
The present ages of A, B and C are in proportions. Eight years ago, the sum of their ages was 76. What are their present ages (in years)?
Choices
Choice (4)  Response  

a. 


b. 


c. 


d. 


Question number: 515
Question
Kamla got married 6 years ago. Today her age is times her age at the time of marriage. Her son’s age is times her age. Her son’s age is ________
Choices
Choice (4)  Response  

a.  5 years 

b.  3 years 

c.  4 years 

d.  2 years 

Question number: 516
Question
2 men and 7 boys can do a piece of work in 14 day, 3 men and 8 boys can do the same in 11 days. 8 men and 6 boys can do 3 times the amount of this work in ________
Choices
Choice (4)  Response  

a.  18 days 

b.  36 days 

c.  24 days 

d.  21 days 

Question number: 517
Question
P is twice good a workman as Q and therefore is able to finish a job in 30 days less than Q. Working together they can do it in ________ days.
Choices
Choice (4)  Response  

a.  40 

b.  50 

c.  20 

d.  30 

Question number: 518
Question
28 integers are chosen from the interval [104,208]. Show that there exit two of them having a common prime divisor.
Choices
Choice (4)  Response  

a.  2 

b.  0 

c.  3 

d.  1 
