IMO Level 1 Mathematics Olympiad (SOF) Class 9: Questions 821  825 of 929
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Question number: 821
Question
In a class test, in mathematics, 10 students scored 75 marks, 12 students scored 60 marks, 8 scored 40 marks and 3 scored 30 marks. The mean of their score is (approximately) ________
Choices
Choice (4)  Response  

a.  57 marks  
b.  15 marks  
c.  56 marks  
d.  54 marks 
Question number: 822
Question
Tea worth Rs. 126 per kg and Rs. 135 per kg are mixed with a third variety in the ratio . If the mixture is worth Rs. 153 per kg, the price of the third variety per kg will be
Choices
Choice (4)  Response  

a.  Rs. 169.50  
b.  Rs. 180  
c.  Rs. 175.50  
d.  Rs. 170 
Question number: 823
Question
Factors of
Choices
Choice (4)  Response  

a. 
 
b. 
 
c. 
 
d. 

Question number: 824
Question
If 3 is added to the denominator of a fraction, the fraction becomes 6. If 4 is added to the numerator, the fraction becomes 30, the fraction is ________.
Choices
Choice (4)  Response  

a. 
 
b. 
 
c. 
 
d. 

Question number: 825
Question
A box contains 8 balls out of which x are black. If one ball is drawn at random from the box, what is the probability that it will be a black ball? If 4 more black balls are put in the box, the probability of drawing a black ball is now double of what is was before, then x is________
Choices
Choice (4)  Response  

a.  6  
b.  3  
c.  9  
d.  2 