Grades 3-4 Video Solutions 2024-2024_3-4

Video Transcription

Question 21. There are exactly two frogs in each row and each column. The frogs decide that two of them will jump to a neighboring empty cell at the same time. Neighboring cells  have a side in common. Afterwards, there still will be exactly two frogs in each row and each column. In how many ways can the frogs do this?  So first, we'll take a look at the top right area of the 3x3 grid. We can see that if the two frogs here jump like so, there will still be two frogs in each column and in each row.  Next, alternatively, the frogs can jump like so, keeping the pattern the same. Instead, the frogs could also jump like so. And finally, the frogs will be able to jump here.  There are no other ways that the frogs could jump, so our answer will be D, 4.

Video Summary

Question 21. There are exactly two frogs in each row and each column. The frogs decide that two of them will jump to a neighboring empty cell at the same time. Neighboring cells have a side in common. Afterwards, there still will be exactly two frogs in each row and each column. In how many ways can the frogs do this? So first, we'll take a look at the top right area of the 3x3 grid. We can see that if the two frogs here jump like so, there will still be two frogs in each column and in each row. Next, alternatively, the frogs can jump like so, keeping the pattern the same. Instead, the frogs could also jump like so. And finally, the frogs will be able to jump here. There are no other ways that the frogs could jump, so our answer will be D, 4.

Keywords

frogs

3x3 grid

jump

rows

columns