Page 25 - 新思维数学学生用书4 样章

Project 1: Deep water

Project 1

Deep water

Here is a picture of a bridge spanning part of the sea at an estuary.

The scale marked on one of the

bridge supports shows the level

of the water. The zero on the scale

is at the base of the bridge. At 2
1
the moment the water is 2 metres 0

below the base of the bridge, –1
–2
shown by the −2 on the scale.

If the water level rose and reached the base of the bridge, how much
would it have risen by?

If the water level then rose again and reached the number 2 on the

scale, how much more would it have risen by? How much would it have

gone up by in total?

The level of the water is checked

2 at midday each day. The picture

1 left shows the water level at
midday on Monday, when it is
0
1 metre below the base of the
–1
bridge. There is a flood overnight,
and by midday on Tuesday the

water level has risen by 2 metres. On Wednesday the flood has finished,

and the water level has fallen by 4 metres from where it was on Tuesday.

Where is the water level at midday on Wednesday?
Can you draw a picture to show what this would look like on the scale?

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