Asked by karen
please help!
1.) A random digit from 1 to 9 (inclusive) is chosen, with all digits being equally likely. The probability that when it's squared it will end with the digit 1.
2.) A random number between 1 and 20 (inclusive) is chosen. The probability that its square root will not be an integer.
1.) A random digit from 1 to 9 (inclusive) is chosen, with all digits being equally likely. The probability that when it's squared it will end with the digit 1.
2.) A random number between 1 and 20 (inclusive) is chosen. The probability that its square root will not be an integer.
Answers
Answered by
MathMate
1. Find how many (initial) digits when squared gives one. Dividing that by 9 will give you the required probability.
Also, it may be of interest to note that single digits that add up to 10 have the same last digits when squared.
Example: 2²=4 8²=(10-2)²=64 also ends with the digit 4.
2. Again, determine how many "perfect squares" there are among the numbers 1 to 20. Divide that number by 20 will give you the probability.
Also, it may be of interest to note that single digits that add up to 10 have the same last digits when squared.
Example: 2²=4 8²=(10-2)²=64 also ends with the digit 4.
2. Again, determine how many "perfect squares" there are among the numbers 1 to 20. Divide that number by 20 will give you the probability.
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