6 CHAP

# 6 CHAP - 6.AVERAGE Ex.1:Find the average of all prime...

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6.AVERAGE Ex.1:Find the average of all prime numbers between 30 and 50? Sol: there are five prime numbers between 30 and 50. They are 31,37,41,43 and 47. Therefore the required average=(31+37+41+43+47)/5 199/5 39.8. Ex.2. find the average of first 40 natural numbers? Sol: sum of first n natural numbers=n(n+1)/2; So,sum of 40 natural numbers=(40*41)/2 820. Therefore the required average=(820/40) 20.5. Ex.3. find the average of first 20 multiples of 7? Sol: Required average =7(1+2+3+…….+20)/20 (7*20*21)/(20*2) (147/2)=73.5. Ex.4. the average of four consecutive even numbers is 27. find the largest of these numbers? Sol: let the numbers be x,x+2,x+4 andx+6. then, (x+(x+2)+(x+4)+(x+6))/4) = 27 (4x+12)/4 = 27 x+3=27 x=24. Therefore the largest number=(x+6)=24+6=30. Ex.5. there are two sections A and B of a class consisting of 36 and 44 students respectively. If the average weight of section A is 40kg and that of section B is 35kg, find the average weight of the whole class? Sol:

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## This note was uploaded on 08/13/2011 for the course FSD 011 taught by Professor Vinh during the Spring '11 term at Beacon FL.

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6 CHAP - 6.AVERAGE Ex.1:Find the average of all prime...

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