Variations

2008-06-06 11:14 am

The cost of painting a metal sphere varies as the square of its radius. It is given that the cost for painting a sphere of radius 3 cm is $150.

a. What is the cost for painting a sphere of radius 4cm?
b. Determine the radius of a sphere that costs $600 for being painted.

solve this thank you. 可以的話請解題意 thanks!

回答 (1)

None

2008-06-06 3:27 pm

✔ 最佳答案

漆一個球體的價錢隨著其半徑的平方而改變如果漆一個半徑3cm的球體要脅$150

問
a 漆一個半徑4cm的球體要多少錢?
b 找出要用$600去漆的球體的半徑是多少

-----

let r cm be the radius
$c be the cost
k be the various ratio

c = k(r^2)

a)
given c = 150 when r=3
150 = k(3^2)
k= 150/9 = 50/3

therefore the cost of a sphere with the radius of 4cm
= 50/3(4^2)
= 800/3
= $266.67 (2 d.p.)

b)
600 = 50/3(r^2)
(600)(3)/50 = r^2
r^2=36
r=6

therefore the radius of the sphere with the painting cost $600 is 6cm

2008-06-06 07:28:33 補充：
第一行多了個"脅"字

👍 0 👎 0