F.2數學2題(20點)

2012-12-05 5:50 am

1.The figure shows a map with scale 1:25 000 000.It is given that the distance on the map between hong Kong and Shanghai is 5 cm.

(a)Find the actual distance between HongKong and Shanghai.

(b)If the distance between Hong Kong and Shanghai on another map with scale 1:n is 12.5 cm,find the value of n.

2.The figure shows the plan of a classroom with scale 1:200.On the plan, the dimensions of the classroom are 3.5cm X 4.5 cm.
(a) Find the actual length and the actual width of the classroom.
(Give the answers in m.)
(b) If a set of lockers of total length 3 m is placed in the classroom, what is the total length in cm of this set of lockers in the plan?

回答 (1)

50418129

2012-12-05 4:52 pm

✔ 最佳答案

(1a)

Let the actual distance be x cm
1 : 25 000 000 = 5 : x
x = 5 x 25 000 000
x = 125 000 000
So, the actual distance is 125 000 000 cm = 1 250 000 m = 1250 km

(1b)

1 : n = 12.5 : 125 000 000
n = 125 000 000 / 12.5
n = 10 000 000

(2a)

Let the actual length be x cm
1 : 200 = 3.5 : x
x = 3.5 x 200
x = 700
So, the actual length is 700 cm = 7 m

Let the actual width be w cm
1 : 200 = 4 : w
x = 4 x 200
x = 800
So, the actual length is 800 cm = 8 m

(2b)

Let the length in the plan be y m
1 : 200 = y : 3
y = 3 / 200
y = 0.015
So, the length in the plan is 0.015 m = 1.5 cm

參考: knowledge

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