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5 Number problem- 4 digit password

Unit 1.1 Number problems and reasoning
The problem

Exam Style question: 

 

Jess has a 4-digit password for her mobile phone. Each digit can be between 0 and 9 inclusive. 

a) How many choices are possible for each digit of the code?

b) What is the total number of 4-digit passwords that Jess can create? 

Jess would like to choose an even number. The code can start with zero. 

c) How many different ways are possible now?

The solution

Solution: 

a) 0-9 digits has 10 different possibilities. 

b) There are 4 digits : 10 x 10 x 10 x10 = 10,000.

c) Even= 0, 2, 4, 6, 8 ; Odd : 1, 3, 5, 7, 9

There are 5 even and 5 odd. 

Even = 510= 12 of the numbers are even.

So,  10,0002  =  5000.

 

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Ruhi Quadri Published on 05 Nov 2020
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