Achieve Week 3&4 #10

[charliea100]

Hi,
I am struggling with the explanation for #10 on the homework. I understand that q=m*Cs*(Tf-Ti). I understand the follow through until the subtraction of 74400J. Can someone explain where this number comes from?

Thanks!

[Audrey Hanna]

It looks to me like they are doing some weird rounding. Essentially, you are just distributing the 1652.68 to the -45.

So -95*4.184=1652.68

->> 1652.68(tf-45)
--> 1652.68Tf - 74370.6 [which they rounded to the nearest hundred?]

It's not really proper to round that way, normally you just round your final answer. Hope this helps!