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# Palindrome is a number that reads the same from right to left

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Senior Manager
Joined: 27 Feb 2014
Posts: 281
Location: India
GMAT 1: 570 Q49 V20
GPA: 3.97
WE: Engineering (Education)
Palindrome is a number that reads the same from right to left  [#permalink]

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16 Feb 2020, 22:55
1
00:00

Difficulty:

55% (hard)

Question Stats:

48% (01:41) correct 52% (01:54) wrong based on 25 sessions

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Palindrome is a number that reads the same from right to left as it does from left to right such as 13431. If a 5-digit number is chosen at random, what is the probability that it will be a palindrome?​

a. 1/10

b. 1/90

c. 1/99

d. 1/100

e. 1/9

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Manager
Joined: 24 Sep 2019
Posts: 89
Re: Palindrome is a number that reads the same from right to left  [#permalink]

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18 Feb 2020, 14:03
1
In terms of probability for a 5 number palindrome, the 2 first and last numbers must be the same which has a 1/10 probability, and the 2nd and 2nd to last numbers must be the same, also a 1/10 probability. To find the probability that a palindrome 5 number will occur at random, multiply the odds of the two conditions:
1/10 * 1/10 = 1/100
Manager
Joined: 22 Sep 2014
Posts: 157
Location: United States (CA)
Palindrome is a number that reads the same from right to left  [#permalink]

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18 Feb 2020, 14:32
ABCAB
A=1,2,3..9......9
B=0,1,2..9.....10
C=0,1,2...9.....10

9*10*10=900

There are 9*10*10*10*10=90000 5-digit numbers

900/90000= 1/100

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Palindrome is a number that reads the same from right to left   [#permalink] 18 Feb 2020, 14:32
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