Any structural or civil engineers here?

[andy_con]

it is, i can do some of it, labeling up etc

but just not all

[FourDee]

ok, i think i misunderstood (language barrier )

[andy_con]

its ok i went to college today, the tutor helped a bit and a few people helped so im now sorted.

many thanks guys

now maths........

fook me its like rocket science!!

[andy_con]

anyone a maths expert on here?

done most of this assignment but am stuck on 8-11

heres what ive got so far - www.laser-man.co.uk/test/assessment4.docx

here are the questions

[danielbriggs]

Here you go; see attached:
Done in rough and in a rush, so may be the odd error or two. I hope you can read my scribbles. I took your values of the standard deviation and the mean to be correct - I didn't work those out again.

Let me know if you want any parts explaining.
Hope that helps,

Dan

[Frixxion]

If you have a Texas Instruments calculator it will do most of this for you

[andy_con]

Daneil,

Im half following and understanding.

214.20 – 214.87 / 0.67212 = 0.9968

Its the next bit i don’t understand

1 – something (0.9968)
Also where did 0.8413 come from??

[danielbriggs]

OK, the Z value (-0.9968) comes from the normal distribution part, and we use statistical tables to look up the corresponding probability value (as the formula is complicated). But you can only look up positive values in the tables.
To find the positive value of Z we can do (1 - z) this gives us a useable number we can look up.
Then whizz down the stats table for a normal distribution and look up the 'phi' value (or as close to as possible.
A Z value of 1 in the table gives us a phi value of 0.8413 i.e. 84%, but we need to do 1-phi(z) = 0.1587 = 15.87%
Does that make sense, it's hard to understand and I'm crap at explaining things...
There are other ways to do this, but I find this the quickest and it's the way I've always done it.

Dan

[danielbriggs]

Here's the table: (attached)

or you could use something like this: http://www.math.unb.ca/~knight/utility/NormTble.htm
But I prefer the format of the one attached

[andy_con]

yeah makes sense, just aint the way the tutor did it.

he used or drew a new histogram chart and did it from that.

but thanks ill work on this