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Activity: Ask all the students in your class to write a 3-digit number. Choose any student from the room at random. What is the probability that the number written by her/him is divisible divisible by digits is  by 3? Remember that a number is divisible by 3, if the sum of its digits are divisible by 3

 

Note : This is an activity, so we assume some values and solve

Let's assume these values

 

Let number of Classmates be 20

 

And numbers written by them are

123, 374, 223, 911, 121, 363, 542, 413, 821, 736, 417, 163, 616, 637, 275, 615, 522, 314, 716, 946

 

So, Total numbers written = 20

 

Now, we know that

Number is divisible by 3 if its sum of digits are divisible by 3

 

Here,

Numbers divisible by 3 are: 123, 363, 417, 615, 522

 

Now,

We need to find Probability that number is divisible by 3

 

Probability that number is divisible by 3 = Number of numbers divisible by 3/ Total numbers

 = 5/20

 = 1/4

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.