Average - General QuestionsAverage - Important Formulas and Facts 1) Average = Sum of observations / Number of observations 2) Suppose an object covers a certain distance at 'a' kmph and an equal distance at 'b' kmph. Then the average speed during the whole journey = $\left(\frac{2ab}{a+b}\right)$
31.The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero ? A) 0 B) 1 C) 10 D) 19 View Answer Report DiscussAnswer: Option DExplanation:Avergae of 20 numbers =0Sum of 20 numbers = 0x20=0it is quite possible that 19 of these numbers may be positive and if their sum is a,then 20th number is -a
32.In Aran's opinion, his weight is greater than 65 kg but less than 72 kg. His brother does not agree with Aran and he thinks that Arum's weight is greater than 60 kg bat less than 70 kg. His mother's view is that his weight cannot be greater than 68 kg. If all of them are correct in their estimation, what is the average of different probable weights of Aran ? A) 67 kg B) 68 kg C) 69 kg D) Data inadequate E) None of these View Answer Report DiscussAnswer: Option EExplanation:Let Arun's weight be x kgAccording to 65<x<72Arun's brother 60<x70Arun's mother x<68The values satisfying all the above condition are 66 and 67.required average= $\frac{66+67}{3}=\frac{133}{2}=66.5$
33.David obtained 76, 65, 82, 67 and 85 marks (out of 100) in English, Mathematics, Physics, Chemistry and Biology. What are his average marks ? A) 65 B) 69 C) 72 D) 76 E) None of these View Answer Report DiscussAnswer: Option EExplanation:Average= $\frac{76+65+82+67+85}{5}=\frac{375}{5}=75$
