陈向东数学里2题求解

kaisandy

1.One number will be chosen randomly from each of the sets above.If x represents the chosen member of set X and y represents the chosen member of set Y,what is the probability that x/y will be an interger?

A.1/16

B.3/8

C.1/2

D.3/4

E.15/16

Data Suffiency

1.见图片

In the figure above,line segments JK and LM represent two positions of the same board leaning against the side KN of a wall.The length of KN is how much greater than the length of MN?

(1)The length of LN is 根号2 meters.

(2)The length of JN is 1 meter.

tonyweng

第一题给图

第二题应该是C吧，根号3-根号2

kaisandy

第一题无视吧

第二题答案是D,所以求解~

nrnr

KJ = ML, as long as the length of KJ or ML can be found, the length difference between KM and MN can be calculated. The difference is KJ * (1/sqrt(2)-1/sqrt(3)).

And KJ = ML = sqrt(2)* LN = sqrt(3)* JN

“sqrt” stands for square root.

So from either condition 1 or 2, we can find out the length of KJ or ML. And then we will know the difference between KM and MN.

I tried to use math symbol in word but cannot copy here. So use some short forms first.

nrnr

Just now I made a mistake when I transferred the formula.

The difference between KM and MN should be KJ* (sqrt(3)/2 – 1/sqrt(2))

kaisandy

same board means KJ=ML?

kaisandy

Thanks!

But one more question,in the sentence,

same board means KJ=ML?