Maths急!!! - Ans.fyi 參考答案

Maths急!!!

2008-08-22 11:19 pm

* I need step plz , thx!
1)write down the common ratio and the 6th term of the geometric sequence:
3 , 6, 12, 24 , 48......

2)A certain kind of organisma dies at a steady rate of 75% every 2 minutes. If there are 1000 organisma initially , find the number of organisms after 8 minutes correct to the nearest tens.

3) the weight od a football player is 88.5kg, correct to the nearest 0.5 kg .

4)Use a suitable estimation method to estimate 9.35 x 11.02. Describe your strategy.

5)Leo uses a ruler on which the distance between 2 successive marking is 5mm to measure the sides of a rectangle and here are the results:
Lethgh = 4.5cm Width = 6.5cm
If he uses the measured lenghts to calcuate the area of the rectangle , find the maximum absolute error.

6) Let x be a positive integer. The possible number(s) that satisfy x<3.9 is/are______.

7) which of the following points lies in the thrid quadrant?
a) 2, -1
b) 4, 3
c) -1, -2
d) -5, 1

Thank You =]

回答 (1)

momo

2008-08-22 11:53 pm

✔ 最佳答案

(1) common difference is 3
6 - 3 = 3
9 - 6 = 3
....
(2)
1000 x (1-0.75)^3
= 15.625
approximate 20 organisms remain
(3)
The weight correct to 0.5kg = 88.5kg
(4)
9.35 x 11.02
estimate = 9.4 x 11= 103.4
11.02 is nearly 11 and 9.35 to say as 9.4
(5)
the error of each measure is 5mm
The length = 4.5 cm 0.5cm = 5cm ~ 4cm
The width = 6.5 cm 0.5 cm = 7cm ~ 6cm
The maximum possible area = 35 sq. cm
The actual area = 6.5 x 4.5 = 29.25 sq. cm
The maximum possible error of the area = 35 - 29.25 = 5.75sq. cm.
(6) the positie integers of x = 3, 2, 1 all of them are smaller than 3.9
(7)
The third quadrant is x and y are negative value
(c) -1, -2 are the point in the third quadrant

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