Grades 3-4 Video Solutions 2012-2012_3-4

Video Transcription

Which of the following numbers can be equal to the number of all the children in this class? 30, 20, 24, 25, or 29. In the class there is Nikolai.  And all the other students in the class can be put into groups of two girls and one boy. Notice they are in groups of three.  The total number of children is a multiple of three plus one. We are going to look at each of the answers and subtract one because of Nikolai.  And see if the remaining number is divisible by three. Starting with 30. 30 minus one is 29. And 29 is not divisible by three. 20 minus one is 19.  That is also not divisible by three. 24 minus one is 23. And that is not divisible by three. 25 minus one is 24. And 24 is divisible by three. Because eight times three is 24.  So this will be the answer. And just to double check we will do E. Which is 28 and that is not divisible by three. Which means our answer is D.

Video Summary

The number of children in the class, given Nikolai and the formation of groups of two girls and one boy, must be a multiple of three plus one. After subtracting one for Nikolai, the number should be divisible by three. Checking each option: 30 minus one equals 29, not divisible by three; 20 minus one equals 19, also not divisible by three; 24 minus one equals 23, not divisible; 25 minus one equals 24, divisible by three (8x3=24); 29 minus one equals 28, not divisible. Thus, the answer is 25, as 25 minus one is divisible by three.

Keywords

children

class

groups

divisible

Nikolai