[Duckin]

ข้อ 1.เค้าบอกว่า ตอบ d) 14/24
ขอโทษนะค่ะ พิมพ์โจทย์ตกไปนิดหน่อย
1. The figure is a solid cube with an edge of length 3, which is made up of small white cubes with edges of length 1. Every face of the large cube is painted black,and the large cube is disassembled. What is the probability that a small cube chosen at random will have an odd number of its faces painted black?
a)1/3 b) 4/9 c) 13/27 d) 14/27 e) 2/3

เค้าเฉลยว่างี้ค่ะ แต่อ่านแล้วก็ไม่เข้าใจ

There would be an odd number of faces painted on the corner pieces. There are 8 corners on the cube. The other type of piece that has an odd numbers of faces painted are the center cubes of each face that have one side painted. There are 6 faces, so there are 6 cubes painted on one side. The total number of cubes with an odd number of faces painted is 8+6 = 14. The problem ability is the number that fulfills the rules over the total number of possibilities. In this case, since there are a total 27 cubes, the probability that one chosen at random has an odd number of sides painted is 14/27, as seen in (D)

ข้อ 2 เข้าใจแล้วคะ ขอบคุณมาก ๆๆๆๆๆๆ เลยนะคะ