Yamy

Don't think its a correct answer!

I agree I) is wrong

Could someone fill the data above into the formula, so we can get an idea how to search the answer? Thank you

Same here, can anyone show how to insert the data into the formulas. Thank you

5.00*10^22 / (gallium level*10^-8)

How did you get the answer? or what is your answer?

Step 1: (0.5*7865 - 7865)/ (193.5 - 7865)= 0.512611614417(erf(ξ)) Step 2: erf(ξ < 0.6), use the approximation erf ξ = ξ Step 3: t= d^2/4*D*ξ^2 t=(59.0x10^-2)^2/4(3.091 x 10^-7)(0.512611614417)^2 t=0.3481/3.2488965297e-07 t=1071440.70862 d=59.0 x 10-2 cm D...

Step 1: (0.5*9110.0 - 9110.0)/ (200.5 - 9110.0)= erf(ξ) Step 2: erf(ξ < 0.6), use the approximation erf ξ = ξ Step 3: t= d^2/4*D*ξ^2 d=88.5 x 10-2 cm D=3.091 x 10-7 cm2/s Step 4: t in sec -> hours Conversion seconds to hours is total/(60x60)

Step 1: (0.5*9110.0 - 9110.0)/ (200.5 - 9110.0)= erf(ξ) Step 2: erf(ξ < 0.6), use the approximation erf ξ = ξ Step 3: t= d^2/4*D*ξ^2 d=88.5 x 10-2 cm D=3.091 x 10-7 cm2/s Step 4: t in sec -> hours Conversion seconds to hours is total/(60x60)