CAT Quantitative Aptitude Questions | CAT Permutation and Combination Questions

The question is from Permutation and Combination. This question is about Sum of Rearrangements. We need to find out the sum of all possible numbers when a four digit number is rearranged. This section hosts a number of questions which are on par with CAT questions in difficulty on CAT Permutation and Combination, and CAT Probability.

Question 27: What is sum of all rearrangements of the 4-digit number 3321?

1. 29999
2. 27777
3. 28888
4. 29997

Explanatory Answer

Method of solving this CAT Question from Permutation and Combination: Clue - FInd the number of rearrangements and then focus on the number of digits

Each of the four digits is likely to appear in the units place , but the digit 3 will appear twice as that of 2 and 1.
Therefore, sum of units place = 3*2 +3*1 + 6*3 = 27.
Sum of tens place = 270
Sum of hundreds place = 2700
Sum of thousands place =27000
Sum of all arrangements of 3321 = 29997.

The question is "What is sum of all rearrangements of the 4-digit number 3321?"

Hence the answer is "29997"

Choice D is the correct answer.