This concept which I'm discussing in this question is common in **O-Level E-Maths** Paper 1.

Just pay attention that we're using **difference** in temperatures compared to height of mountain.

**General knowledge: **As we ascend the mountain, the temperature drops. In other words, the higher you're on a mountain, the colder it gets.

I hope you find the step by step solution easy to understand.

Han Zhihao says

An alternative is to plot a graph and everything becomes simple!

edmund says

can we use gradient to find the temperature instead?

Han Zhihao says

That's insufficient. Form a table first. For me, I use x-axis as ht, y-axis as temp.Sketch the graph. From there, construct the y=mx+c equation. Sub in the y value and you will get the x!

ps:This method is 'widely used' in lab, where they put in a value into the computer and they get the end result!

Han Zhihao says

The type of questions that have a hint of direct proportion indicates the use of this method. Might be a bit longwinded but will ease confusion.

huining says

how do i deal with this qns if they asked ! what is the temperature at for instance 1500 m ! can you demonstrate it here!urgent!damn weak in this

edmund says

i dont know how to attach the image file here. roughly the steps are:

1) sketch the graph of ht vs temp. Indicate three points: A(-16,3250); B(-10, h) & C(10,0) on the linear line, where h denotes the ht at -10 deg. C

2) calcuate for h :

gradient AB = gradient AC

(h-3250)/[(-10-(-16)] = (3250-0)/(-16-10)

h-3250 = -750

so, h = 2500 metres

Han Zhihao says

Also can.