Grimweasel

Okay I know the SDT triangle but what I am after is any easier way of doing the maths very quickly mentally. This seems like the best place to ask what with all the Nav's and pilots etc.

How does one quickly work out Time if you have travelled 50 miles at 90mph?

Are there any easy ways bar learning all the distances travelled at each MPH or that at 60mph you are doing 1 mile per minute etc?

Forgive my lack of mathmatical ability, its just so easy with a calculator , its just OASC doesn't allow them!!

BEagle

Use miles per minute and fractions. Also applying percentage differences will help if the numbers are awkward...

50 miles at 90 mph? That's 50 at 1 1/2 (or 3/2) miles per minute. So, what's 50 x 2/3?

kph to mph? Multiply by .7, and knock off a tenth. So 80 kph is 56 minus 5.6 or roughly 50 mph.

Sashathehungry

hmmm... not really any shortcuts, but doing such sums repeatedly in your head does help eventually (I know it did for me when I went to OASC).

For the 90mph 50 mile question, and referring to the fact that 60mph is 1 mile per minute, you are effectively doing 90/60 miles per minute, or 1.5. Divide 50 by that (which is the same as multiplying by 2/3) and you get 33mins and 20 secs.

Alternatively you could divide 50 by 90 and multiply that by 60.

Sometimes fractions are a better way of getting a near (if not totally correct) answer... At least that's what I find.

Work through some examples and find a system that best suits you.

Gosh I sound like my maths teacher!

Hope this helps, all the best with OASC

Hungry

EDIT:
BEagle just saw your post...glad to see I'm not too rusty

Big Cheese1

From what I gathered, the speed/distance/time questions are rather basic, which shouldn't take much working out at all.

Anyone know otherwise??

Still, no harm in being prepared for any type of q's is there!!

Good luck Grimweasel, who knows, may see you there

whowhenwhy

First off you can help yourself out by being familiar with numberwork. By which I mean do lots of mental arithmetic between now and OASC. I seem to remember the other thing that I was told to do was practise times tables of multiples of 6 ie. 6x, 12x, 18x. Apparently a lot of the questions revolve around multiples of 6?!?! Someone confirm if they can? The other thing that you can do is play computer games that will help you to practise hand-eye coordination. Of course they have to be a certain kind of game, I don't believe that playing Lemmings or Las Vegas strip poker will help much!

SirToppamHat

The ones I always used to struggle with were those that involved calculating the position that things will meet. For example, car leaves point A and travels towards point B at 20mph, at the same time, a cyclist leaves point B and travels towards A at 8 mph. The distance between A and B is 70 miles. Where will they cross?

The motorist is travelling two and a half times faster than the cyclist, (20/8 =2.5) so for every 10 miles travelled by the motorist, the cyclist travels 4. The trick is to ADD the ratio of speeds together (2.5+1=3.5), then divide the total distance by the ratio. 70/3.5 =140/7=20. The cyclist will travel 1 x 20 miles, whilst the motorist travels 2.5 x 20 miles (50 miles).

I wondered at the time what the aim of these questions was, but consider the following:

Target ac 800 nm away, approaching at 400knots, fighter travels at 540 knots but takes 15 mins to get airborne after scramble. What time do we scramble to meet the target at the edge of our Air Policing Area (say) 250 nm out? It is 1200Z, allow 15 minutes launch time. For the purpose of the exercise, there is no significant wind. You may use a calculator. Answers on a postcard please ....

I also remember at Biggin Hill being presented with a theoretical problem that I had to work on then present a verbal solution to the Boarding Officers. It involved transport and distance calcs as above, but my solution ended with an MP being picked up from the train station on the back of a motorbike. Not ideal, but it worked ... right up to the moment when the Wg Cdr pointed out that the MP was Margaret Thatcher! The only response I had was '******'.

sarboy w****r

Using fractions is by far the easiest way to work it out.

Speed is generally expressed as miles per hour. Most of the questions involve distances that are far less than the distance you will travel in one hour. It is far easier to work out the answer when speed is expressed as miles per minute.

90 mph is 90 miles in 60 minutes. 90/60 = 3/2 miles/minute.

So in 2 minutes you will travel 3 miles.

Time = Distance / speed.

Dividing by a fraction is the same as multiplying by its reciprocal. So for example, 12 divided by 3/2 is the same as 12 multiplied by 2/3 (=8).

If you're given a distance and you need to work out the time taken to travel the distance then multiply by the reciprocal.

E.g. Time taken to travel 60 miles at 100 mph?

100 mph = 100/60 = 5/3 = 5 miles in 3 mins.

Time = 60 / (5/3)

= 60 x (3/5) = 36 mins.

By using this method you can quickly work all answers for even the most awkward of speeds. It's just a matter of how well you can multiply and divide. And that takes practice...

With the problem solving exercise, if you have worked out the speeds of all the characters involved before you go to present the solution to the board it can be a big help. Particularly when they throw random questions at you.

If you should end up with fractions of hours, and you need to express things in minutes, it can help to remember that 0.1 of an hour is 6 mins.

If in doubt, just practice your times tables (up to 12). And again... and again... and again... until your maths is slick. How badly to you want to pass OASC?

SBW

BEagle

Very wise words indeed, sarboy w****r!!

An inability to solve problems using mental arithmetic is symptomatic of current edyookayshun standards for digi-yoof, I'm afraid.

Try teaching MDR to someone who has no idea what a non-digital clock face looks like........

johnfairr

GW,

I don't know if you do much driving, but one of the best ways of practising is when on motorways to continually update your ETA for any point. In these days of on-board trip computers etc, a little bit of mental maths can make the journey fly by. Also, if you have a range/consumption facility, you can do a "howgozit" on the fuel as well.

Knowing that BEagle has a sleek Mercedes, I am sure he continually checks the readings from the ghost in the machine with his own in-built cpu to make sure they co-relate and that way every trip you make can sharpen your mental skills. It can also impress the odd female passenger when you tell her, upon leaving pub/disco/wine-bar, that she'll be home at 11:23 precisely, and you are always right! Judicious use of the go/stop pedals mean that you deliver her to her place spot on time.

Grimweasel

Many thanks to all.........

Life would have been easier had be done more fractions at school. My maths teacher was a great believer in moving forward with the times. In the future (computers and all that) fractions will become obsolete he'd say. Decimals were the way forward. Well thats fine mit calculator but when faced with dividing a small number with a large one it becomes a little more difficult. Such as 40 / 120 to give a nought point something?

I'll brush up on my fractions..

Pom Pax

Hints
Think in six minutes 1/10 of a hour
2 moving objects, stop one and transfer its relative velocity to the other. Approching add, same way subtract.
Remember x km = y miles = z nm see the back of a wizz wheel, something like 126, 78, 68.
60 mph = 88 ft/sec

Always_broken_in_wilts

Good advice given to me was to purchase some books from WH Smiths titled "Know your own IQ", or I think that was the title. Not very useful in establishing an accurate picture as I, eventually , scored quite well but it definately helped establish the thought process required to solve some of the mental agility problem that Biggin Hill presented at that time.

Hope it all goes well at OASC

all spelling mistakes are "df" alcohol induced

teeteringhead

A lot of civilian firms now include "Numeracy assessment" in their selection process (just been there, just done that!), so there are handy booklets available in the "Business" section of your local W~t*rst#n*s or whoever.

They seem to have catchy titles like "How to do well in Numeracy Assessment", and the sums are business rather than aviation, but basic principles are the same; you may find them useful.

The mother alligator

I was at OASC in December, and the maths that I had to do was not too taxing. Although, this is obviously my own opinion, and there is certainly not much chance of you getting the same problems that I did. When you're faced with devisions like 40/120, cancelling down will make this devision a dream. First of all cancel by 10, giving 4/12, then by four, giving 1/3, which is 33%. Learn how to convert fractions/percentages of hours/minutes into hours and minutes. In this case, for instance, 33.3% or 1/3 of an hour is 20 minutes, a minute, 20 seconds.
PM if you are still in desperate need of help. Work hard, and you will get it, I did.
TMA

Toxteth O'Grady

What is the easiest way to calculate the distance between two points?

Calculate the distance halfway, then double it.

willbav8r

Math went well for TMA but not English; obviously..........

Mr C Hinecap

Please - somebody tell me this is a joke. I'm not sure I can wait for the couple more years until mooney is telling us how the RAF unfairly chopped them at selection