A Prime Number between 10 and 50 remains unchanged if its digits are reversed

A prime number between 10 and 50 remains unchanged if its digits are reversed. Then the square of such a number is

  • 121
  • 484
  • 1089
  • 1936
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1 Answer(s)

. The value of X = 50

Solution-

Formula of Average =    (sum of observation/No. of observation)

Observations= 5, 10, 15 and X.

No. of observation= 4

Sum of observation = 5+10+15+X.

Average = 20     (Given)

(5+10+15+X)/4 = 20

(30 + x)/4 = 20

30+x = 20×4

X = 80 – 30

X = 50            Ans.

Anurag Mishra Professor Answered on 5th May 2015.
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