Mystery Triangle Hole (Misteri Lubang Segitiga)

Perhatikan gambar di atas! Gambar puzzle (teka-teki) tersebut dinamakan Mystery Triangle Hole (Misteri Lubang Segitiga). Dari manakah berasal lubang misterius pada gambar kedua (di bawah)?

Mungkin Anda sudah tahu jawabannya. Bagi yang belum tahu jawabannya dan penasaran ingin tahun jawabnnya, Silakan simak jawabannya di bawah ini!

Perhatikan gambar di atas. Dari manakah persegi panjang yang berwarna putih? 

Bangun bagian atas merupakan segi emapat cekung, sedangkan bangun bagian bawah merupakan segi empat cembung. Segi empat bagian bawah (cembung) lebih luas dari pada segi empat bagian atas (cekung). Selisih luasnya adalah 2 satuan. Selisih luas itulah berupa persegi panjang yang berwarna putih.

Sekarang perhatikan gambar pada Mystery Triangle Hole! Gambar bagian atas sebenarnya bukan seitiga, melainkan segi emapat cekung, sedangkan gambar bagian bawah merupakan segi empat cembung. Selisih luasnya adalah 1 satuan. Selisih luas itulah berupa lubang (bebentuk persegi) yang berwarna putih. 

Bukti Bahwa Kedua Bangun Bukan Segitiga

Perhatikan lagi gambar pada Mystery Triangle Hole! segitiga warna merah dan segitiga warna hijau kemiringannya  (gradiennya) tidak sama. Kemiringan segitiga merah = 3/8 = 0,375 sedangkan kemiringan segitiga hijau = 2/5 = 0,4. Oleh karena itu sisi miring segitiga warna merah dan segitiga warna hijau (bila disambung) bukan merupakan garis lurus, sehingga bangun yang terbentuk bukan segitiga, melainkan segiempat. 

Masih belum yakin bahwa kedua bangun itu bukan segitiga? Buka aplikasi pengolah gambar (misal photoshop). Tariklah garis sehingga tampak seperti gambar di bawah ini:

Smith Jones Robinson

2^nd in Logic series

On a train, Smith, Robinson and Jones are the fireman, brakeman, and engineer, but NOT respectively. Also aboard the train are three businessmen who have the same names: a Mr. Smith, a Mr. Robinson,and a Mr. Jones.
1. Mr. Robinson lives in Detroit
2. The brakeman lives exactly half way between Chicago and Detroit.
3. Mr. Jones earns exactly $20,000 per year.
4. The brakeman's nearest neighbor(city-wise), one of the passengers, earns exactly three times as much as the brakeman.
5. Smith beats the fireman at billiards.
6. The passenger whose name is the same as the brakeman's lives in Chicago.

Question:Who is the engineer?

Light Bulb

3^rd in Logic series

A light bulb is hanging in a room. Outside of the room there are three switches, of which only one is connected to the lamp. In the starting situation, all switches are 'off' and the bulb is not lit.

Question: If it is allowed to check in the room only once to see if the bulb is lit or not (this is not visible from the outside), how can you determine with which of the three switches the light bulb can be switched on?

Mystery Triangle Hole

4^th in Logic series

The two triangles shown in the image look exactly similar. They are made up of the same parts.

Question: Where does the mysterious hole come from in the second picture?

Lean-Eyed painter

5^th in Logic series

A painter painted everything leaner than what it was (aspect ratio length:height=x<1). Someone suggested that it might be because he is seeing the world like that.

Question: It can't be true. Tell us why?

Notes : Reference given in the solution.

4 men crossing a bridge

6^th in Logic series

(Well, this one borders on the next series: geometric.) There are 4 men who want to cross a bridge. They all begin on the same side. It is night. There is one flashlight. A maximum of two people can cross at one time.
Any party who crosses, either 1 or 2 people, must have the flashlight with them. The flashlight must be walked back and forth, it cannot be thrown, etc. Each man walks at a different speed. A pair must walk together at the rate of the slower man's pace.
Man 1: 1 minute to cross
Man 2: 2 minutes to cross
Man 3: 5 minutes to cross
Man 4: 10 minutes to cross
For example if Man 1 and Man 4 walk across first. 10 minutes have elapsed when they get to the other side of the bridge. If Man 4 returns with the flashlight. A total of 20 minutes have passed and you have failed the mission.

Question: Can you complete the mission in 17 minutes?

Notes : Reference given in the solution.