Personal Links
Browse Teasers
Search Teasers

Class Photo 2

Logic puzzles require you to think. You will have to be logical in your reasoning.

 Puzzle ID: #43969 Fun: (1.94) Difficulty: (2.5) Category: Logic Submitted By: cnmne

Kevin's class picture has 28 photos arranged in a 7 x 4 grid. The photos in the top row are numbered 1 through 7 from left to right, with the photos in the remaining rows similarly numbered. Given the following clues (bordering includes horizontal, vertical, and diagonal), where is Kevin's picture?

X X X X X X X (1 - 7)
X X X X X X X (8 - 14)
X X X X X X X (15 - 21)
X X X X X X X (22 - 28)

1) There are 11 boys and 17 girls.
2) No boy is next to another boy horizontally or vertically.
3) There are no more than three boys in each row.
4) One column has only girls.
5) Three boys are not along the edge of the picture.
6) The second boy is at an odd position.
7) The range of the boys' positions is 24.
8) The median of the boys' positions is 12 or 13 or 14.
9) There are boys in two corners.
10) Kevin occupies an even position, and is the only boy who borders a unique number of girls.

Answer

A) There are five boys prior to the median, meaning that there are three boys in each of the first two rows. If the first boy is at location 4, then there could only be two boys in the first row. The first boy must be located before position 4, therefore a girl must occupy: 28 (clue 7). The second boy can not be at position 4 (clue 6). The earliest position that the third boy could occupy is position 5. Therefore, a girl must occupy: 4.
B) If boys are at positions 1 (a corner) and 25 (clue 7), then a boy would have to be at either position 7 or 22 (clue 9). In either case, more than three boys would not be along the edge of the picture, violating clue 5. Therefore, a girl must occupy: 1. Boys must occupy: 7 and 22 (clue 9). Girls must occupy: 6, 14, 15, and 23.
C) For three boys to be in the first row, the second boy must occupy: 5 (which also satisfies clue 6). A girl must occupy 12. Per clue 8, a boy must occupy: 13. A girl must occupy: 20. To avoid violating clue 5, boys must occupy: 8 and 21. A girl must occupy: 9.
D) Clues 8 and 9 have now been satisfied, and 16 of the 28 positions have been filled. To satisfy clues 1 through 7, the last 12 positions can be filled in four different ways. However, only one of those ways will satisfy clue 10. In the three ways that do not work, the boy that borders a unique number of girls is located at an odd position.

Step A Step B Step C Step D
xxxGxxx GxxGxGB GxxGBGB GBGGBGB
xxxxxxx xxxxxxG BGxxGBG BGBGGBG
xxxxxxx Gxxxxxx GxxxxGB GBGGGGB
xxxxxxG BGxxxxG BGxxxxG BGBGBGG

The boys in the first row border (3, 4, 2) girls.
The boys in the second row border (3, 6, 5) girls.
The boys in the third row border (4, 4) girls.
The boys in the fourth row border (2, 4, 5) girls.

The only boy that borders a unique number of girls is the boy who borders six girls, which is at position 10. Kevin is at position 10.

Hide

What Next?

See another brain teaser just like this one...

Or, just get a random brain teaser

If you become a registered user you can vote on this brain teaser, keep track of
which ones you have seen, and even make your own.

Comments

 fame Jan 22, 2009 th8svfujhgf EnderofGames Jan 26, 2009 Lol, the answer diagrams are screwed up a bit... You might want to try to get them on different lines. Or ask to get it imaged. Good teaser, though, really liked it. june12 Jan 27, 2009 hard but i enjoyed it...my head kinda hurts

Back to Top

Users in Chat : Katherine24

Online Now: 7 users and 330 guests

Custom Search