# Maths Question

Answers provided with a picture to solve this appreciated.

A1 the cost of connecting a call.

I donâ€™t understand.

The intercept looks like 0.5, the gradient is 6/4,so 1.5.

Therefore the formula is y=1.5x + 0.5

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a i) the graph intercepts the y axis at 50p this the starting charge for any call

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What @carstuckindrive said ^

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Can this be answered with a picture on the graph?

I donâ€™t understand. You could enlarge the point at which the line crosses the Y-axis, I guess.

(looks more like 0.5 than 0.6 to my eyes, but my eyes are bad)

Oh, do you mean, why would this be the case? As @carstuckindrive says, thereâ€™s a one-off, minimum, charge for connecting the call (the intercept), then a per minute rate beyond that (the gradient).

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Never my best subject, thanks for the replies.

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Has to be 0.5 because it clearly goes through (2,1) and (8,5) and is linear.

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On second looking at it I think it is 50p!

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ii) gradient is 6/4, so 1.5.

Calls cost 1.5 per minute

Closest thing I can think of that would fit this would be to draw dimension lines measuring along for an x value and up for a y value (ending up with a right angled triangle under or over the given plotted line) to show where youâ€™re getting your values from for calculating gradient (m) = change in y Ă· change in x.

And maybe a horizontal line across from the y-axis intercept labelled c=0.5.

i.e. this

In the question, â€śGive an interpretation ofâ€¦â€ť is a needlessly complicated way saying â€śWhat is theâ€¦â€ť.

And part (b) of the question is needless repetition.

Also, fuck that graph for not having labels on the axes (or a title). Putting the â€śÂŁy for x minutesâ€ť text underneath is no excuse.

A very irksome way of testing the understanding of a concept, this.

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My brain isnâ€™t up to this.

The fact every number of the Y-Axis is half the number on the X-Axis (i.e. the X-axis is counting 1cm at a time while the Y-Axis is counting every 0.5cm or something like that) has already made it melt and dribble out of my ears. Gradient seems to therefore be 6/8 not 6/4 since itâ€™s a reflection of equal measurements not numbers. Or does that make this logarithmic?

@colinfilth will know.

Gradient is 6/4 as wza says.

No neither scale is logarithmic, they are both linear.

Yes the scaling and labelling on the graph are both poor and needlessly confusing.

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I reckon the fact that the scales are similar (only half/double each other) and covering a similar range (neither reaching more than single figures) is what makes it fiddly/confusing. Your brain is tempted toward instinctual remembered shortcuts rather than going by the step by step method through the maths of it.

Almost becomes a trick rather than a test of understanding.

Itâ€™d be less odd-seeming if the x axis were measuring something other than phone call duration and covered a range of 0-500 days, for example.

Going by the BBC Bitesize page, this is Key Stage 3, 11 to 14 year-olds. Seems like a completely reasonable concept for them to take on. But the presentation and communication in that question is awful.

Especially that â€śGive an interpretation ofâ€¦â€ť bit. Infuriating. Sounds more like a philosophy question. Just bloody ask what it is you want to know. Like â€śWhat is the fixed cost, in pence, shown on the y-axis, that applies to all calls made before any time has elapsed.â€ť Something like that.

TBH I hope a lot of that is because teachers are given a syllabus that includes teaching concepts certain ways and, in theory at least, the papers and exams should be checking if you learned the ways.

I remember at A-Level looking at some late 80s past papers for our board. The questions were really hard but part of that was they were just asking questions in a way we hadnâ€™t been asked to.

I remember there was a general thing with some teachers claiming it was just the exams had got easier but others said it was all the same concepts it was just the approach that changed.

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I guess the devilâ€™s advocate answer to this is it gives scope for flexibility when reading the answers. Would really need to see the marking notes to work out whatâ€™s going on there. Also I think a key part of the question there is identifying that the intercept is a fixed cost, rather than simply asking how much it is.

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