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# How to find the value of R ?

Asked by dashty on 17 Feb 2013

If

```R1 = 0.173*(E^3/2)*A1^1/3
R2 = 0.173*(E^3/2)*A2^1/3
R3 = 0.173*(E^3/2)*A3^1/3
Wi = (Ni*Ai)/M
```
```for R1    Ni = 10  & A1 = 12
for R2    N2 = 8   & A2 = 1
foe R3    N3 = 4   & A3 = 16
M = sum(Ni*Ri)
E = ( 1,2,...,10)
```

Then

```1/R = sum(wi/Ri)
```

Find R

Greg Heath on 17 Feb 2013

Please separate equations by putting them on separate lines.

Thanks.

Walter Roberson on 17 Feb 2013

Reformatted, but they are hard to interpret that way too.

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Answer by Carlos on 18 Feb 2013

Is this what you mean?

```>> A=27;
>> E=1:1:10;
>> R = 0.173*(E.^3/2)*A.^1/3
```
```R =
```
`    Columns 1 through 9`
`      0.7785    6.2280   21.0195   49.8240   97.3125  168.1560  267.0255  398.5920  567.5265`
`    Column 10`
`    778.5000`

Answer by Tae Yeong Kim on 17 Feb 2013
Edited by Tae Yeong Kim on 17 Feb 2013

It is very hard to interpret the equations. Could you form the equations neatly?

Answer by Image Analyst on 17 Feb 2013

Isn't it just

```R = 1 ./ sum(wi./Ri)
```

????? Of course that assumes you already know what wi and Ri are, which none of us do.

Answer by Walter Roberson on 17 Feb 2013
```N = [10 8 4]
A = [12 1 16];
R = ??
M = sum(R .* N);
W = (N .* A) ./ M;
Final_R = 1 ./ sum(W .* R);
```

Unfortunately the definition of R(i) is confused as it is based upon E which appears to be 1:10.

Answer by dashty on 18 Feb 2013

Thanks for all I need the value of R in this equation

R = 0.173*(E^3/2)*A^1/3

If the value of A = 27 and

E= (1,2,3,4,5,6,7,8,9,10)