AZABU-2010

(2) Write in all the right dodecagons that have every side on the dotted line in the figure.

Problem 2

Taro and Jiro left A town at the same time and went to B town.

Taro went by bicycle and Jiro went on foot.

The ratio of the speed of Taro and Jiro is 5 : 1.

As Taro noticed that he left something at point P on the way, he returned toward A town and passed each other with Jiro 4 minutes afterward.

Taro returned to A town and went to B town again.

Taro caught up with Jiro at Q point and he arrived at B town 24 minutes earlier than Jiro.

Two persons shall move with fixed speed, respectively.

Answer the following questions.

(1) Find the time after leaving when Taro returned at P point.

(2) If the distance from A town to Q point sets to 800 m, find the distance from A town to B town.

Problem 3

There is a paper tape 1 m in length.

After marking the points where this tape is divided into three equal parts , five equal parts and seven equal parts, respectively, this tape is cut off at the point marked.

Find all the kinds of length of the tape after cutting.

Problem 4

Black and white squares whose length of one side is 1 cm are spread as shown in a figure.

In each figure of (1) to (3) shown by the bold line, comparing the area of black(shadow) and white, which is larger by how much or same?