IMO Level 1 Mathematics Olympiad (SOF) Class 9: Questions 239  243 of 929
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Question number: 239
Question
27 metal balls each of radius r are melted together to from one big sphere of radius R. Then the ratio of surface area of the big sphere to that of a ball is ________
Choices
Choice (4)  Response  

a.  3  
b. 
 
c. 
 
d.  9 
Question number: 240
» Lines, Angles and Quadrilaterals
Question
A running track is the ring formed by two concentric circles. It is 15 feet wide. The circumferences of the two circles differ by about ________
Choices
Choice (4)  Response  

a.  65 feet  
b.  94 feet  
c.  75 feet  
d.  90 feet 
Question number: 241
» Lines, Angles and Quadrilaterals
Question
From the adjoining figure . The value of x is ________
Choices
Choice (4)  Response  

a. 
 
b. 
 
c. 
 
d. 

Question number: 242
Question
A rectangle is divided into four smaller rectangles, as shown in the figure. Three of them have areas , and as indicated. Then the area of the shaded rectangle is ________
Choices
Choice (4)  Response  

a. 
 
b. 
 
c. 
 
d. 

Question number: 243
Question
C1 is a circle of radius 4 cm, C2 is a circle of radius 12 cm. Jyoti wants the two circles to touch tangentially. She knows that there are two possibilities for the distance between their centers. What are these two distances?
Choices
Choice (4)  Response  

a.  8 cm and 16 cm  
b.  10 cm and 16 cm  
c.  8 cm and 10 cm  
d.  13 cm and 4 cm 