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 = $\left(\frac{2ab}{a+b}\right)$
6.The average age of a husband and his wife was 23 years at the time of their marriage. After five years they have a one-year old child. The average age of the family now is : A) 19 years B) 23 years C) 28.5 years D) 29.3 years View Answer Report DiscussAnswer: Option AExplanation:Sum of the present ages of husband wife and child = 23x2+5x2+1=57 years Required average =57/3= 19 years
7.Of the three numbers, the average of the first and the second is greater than the average of the second and the third by 15. What is the difference between the fire and the third of the three numbers ? A) 15 B) 45 C) 60 D) Data inadequate E) None of these View Answer Report DiscussAnswer: Option EExplanation:let the number be x,y,zThen $\frac{x+y}{2}-\frac{y+z}{2}=15$(x+y)-(y+z)=30x-z = 30
8.Of the three numbers, the first is twice the second and the second is twice the three. The average of the reciprocal of the numbers is 7/72. The numbers are : A) 16, 8, 4 B) 20, 10, 5 C) 24, 12, 6 D) 36, 18, 9 View Answer Report DiscussAnswer: Option CExplanation:Let the third number be x .Then second number = 2x First number = 4x $\frac{1}{x}+\frac{1}{2x}+\frac{1}{4x}=\frac{7}{72}\times3$$\frac{7}{4x}=\frac{7}{24}$4x=24x=6So the number are 24,12 and 6
9.The average price of three items of furniture is Rs. 15000. If their prices are in the ratio 3:5:7, the price of the cheapest item is : A) Rs. 9000 B) Rs. 15000 C) Rs. 18000 D) Rs. 21000 View Answer Report DiscussAnswer: Option AExplanation:let their prices be 3x,5x and 7xThen 3x+5x+7x = 15000x3x=3000COst of the cheapest item =3x= 9000
10.In the first 10 overs of a cricket game, the run rate was only 3.2. What should be the run rate in the remaining 40 overs to reach the target of 282 runs ? A) 6.25 B) 6.5 C) 6.75 D) 7 View Answer Report DiscussAnswer: Option AExplanation:Required rate = $\frac{282-(3.2\times10)}{40}=\frac{250}{40}=6.25$