math
posted by student .
Estimate 16 20/21*28 3/7  4 13/25 + 8 2/47 as a whole number or as a mixed number whee the fractional part is 1/2.
a. 452
b.480
c.488
d.492 1/2
I would say the answer is c  488. Would that be right?

the * means times, right?

yes

yes, that is what we use in class instead of x when we are are on the computer.

Assuming it does, I multiplied and got 10120.alotmore#s. Did you get the same thing? Did you round after that? (I multiplied 16 20/21 and 28 3/7)

I really don't know if you copied the question wrong or something because when I did the question 3 times total and keyed the fractions into my calculator I get the same answer of
485.45 so I don't know if either the multiple choice is incorrect or the copied question is wrong but something is funny. 
Posting my work on this:
16 20/21*28 3/7  4 13/25 + 8 2/47 =
(356/21)*(199/7)(133/25)+(378/47)=
(70844/147)(133/25)+(378/47)=
484.654
(this is most likely the answer to this question that you posted [it may have been copied wrong] because I'm using my TI83 Plus graphing calculator to just straight punch in the fractions(it can handle large fractions) while before I was using a normal calculator)
note it's not there as a choice so I personally feel that it's a problem with the question/ multiple choice 
What's a common denominator of 25 and 47?

I'm not sure but a foolproof way to go and use a denominator common to both is to go and
multiply both numbers
here: 25x47=1175 
thanks! but now I just realized that if I find the common denominator of those two numbers, I'm not following PEMDAS, so hold on, I have to rethink this.

Okay, I have to get off the computer now, but I hope this which I figured so far will help you find the answer:
I multiplied 16 20/21 and 28 3/7. I got the fraction 212532 over 21.
Next, you subtract 4 13/25 from 212532 over 21, I think. Once you've done that, add 8 2/47, and you should get a matching answer. Hopefully. Or else there's seriously something wrong about the whole question, like, it had to have been misprinted or typed incorrectly or something. Good Luck! I'll work on it more tonight and I'll check back probably tomorrow. 
Brie the 2 fractions multiplied is NOT what you got...are you using a calculator?