Anonymous
Anonymous asked in 科學及數學數學 · 8 years ago

緊急, 數學高手請幫幫手

1. In the mysterious lost city of Mim, the length of daylight (in hours) on the

圖片參考:http://r140.n100.queensu.ca:8081/wwtmp/equations/e...

Use this model to compare how the number of hours of daylight is increasing on March 16 and June 2 (assume that this is a standard year, not a leap year).

2. A Norman window has the shape of a semicircle atop a rectangle so that the diameterof the semicircle is equal to the width of the rectangle. What is the area of the largestpossible Norman window with a perimeter of 48 feet?

1 Answer

Rating
  • Kevin
    Lv 7
    8 years ago
    Favorite Answer

    It is better to use the negation and the fact P(AUB) = P(A) + P(B) - P(A∩B) in this question

    No restriction:

    Number of all possible arrangements = 7P7 = 5040

    V is at its original position:

    Number of possible arrangements = 6P6 = 720

    T is at its original position:

    Number of possible arrangements = 6P6 = 720

    V and T are both at their original position:

    Number of possible arrangements = 5P5 = 120

    Applying P(AUB) = P(A) + P(B) - P(A∩B),

    Either V or T is at its original position:

    Number of possible arrangements = 720+720-120 = 1320

    Using the negation,

    Number of possible arrangements = 5040-1320 = 3720Another method:

    T is at the first place:

    V can be at any other place, number of possible arrangements = 6P6 = 720

    T is at the 2,3,5,6,7th place(5P1):

    V can be at any other place except the first, number of possible arrangements = 5P1*5P1*5P5 = 3000

    adding all cases and get 720+3000 = 3720

    • Login to reply the answers
Still have questions? Get your answers by asking now.