Question

There are thirteen 2-digit consecutive odd numbers. If 39 is the mean of the first live such numbers, then what is the mean of all the thirteen numbers?

Answer 1

Answer:

49

Step-by-step explanation:

let one of the no.s is x

take the 1st 5 no.s as x, x+1, x+2, x+3 and x+4.

mean of the no.s =39(in question)

(x+x+1+ x+2+x+3+x+4)/5=39

(5x+10)/5=39

5(x+2)=39×5

x+2=39

x=37

so the 13 nos are: 37 39 41 43 45 47 49 51 53 55 57 59 and 61.

their mean:

(37 +39+ 41 +43 +45 +47 +49+ 51 53 +55+ 57 +59 +61)/13=47

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Answer 2

Answer: 47

Step-by-step explanation:

let one of the no.s is x

take the 1st 5 no.s as x, x+2, x+4, x+5 and x+8(since consecutive but odd...difference has to be 2)

mean of the no.s =39(in question)

(x+x+2+ x+4+x+6+x+8)/5=39

(5x+20)/5=39

5(x+4)=39×5

x+4=39

x=35

so the 13 nos are: 35 37 39 41 43 45 47 49 51 53 55 57 and 59.

their mean:

(35+37 +39+ 41 +43 +45 +47 +49+ 51 53 +55+ 57 +59 )/13=47