Bacteria Multiplying/OG

[jamesrwrightiii]

I had a quick question regarding the answer in the book.

Problem is as follows

A certain population of bacteria doubles every 10 minutes. If the number of the bacteria in the population was 10^4, what was the number in the population 1 hour later?

A. 2 (10^4)
B. 6 (10^4)
C. 2^6*10^4
D. (10^6)(10^4)
E. (10^4)^6

I chose D as the answer because I thought it would be 10^10? Where did I go wrong?

[kittie]

The bacteria doubles every 10 mins.
If the initial number is x, after 10 mins it becomes 2x, after 20mins it becomes 4x...and after 60mins it is 2^6x
Here x = 10^4
hence final answer must be = 2^6 * 10^4.

Is the C the answer?

[Ashoka]

'C' for me.

[Dimas]

I had a quick question regarding the answer in the book.

Problem is as follows

A certain population of bacteria doubles every 10 minutes. If the number of the bacteria in the population was 10^4, what was the number in the population 1 hour later?

A. 2 (10^4)
B. 6 (10^4)
C. 2^6*10^4
D. (10^6)(10^4)
E. (10^4)^6

I chose D as the answer because I thought it would be 10^10? Where did I go wrong?

It is C. I think you misunderstood the twem doubled. If X doubled it becomes 2X. If it is doubled again it becomes 4X. So on....

[henryhuang]

same as c

In how many ways can 5 rings be worn on four fingers of the right hand?
A.3*4
B.5C4
C.5P4
D.5^4
E.4^5
Ans is E. Can someone explain? Thanks.

[pach2212]

Choose 1 ring at a time,
The first one can go to any of the 4 fingers. So we have 4 ways for the first one.
The second one can go to any of the 4 fingers. So we have 4 ways for the second one.
and so on for all 5 rings.

By fundamental counting principle, we have 4*4*4*4*4 ways = 4^5 ways.

Hope this is lucid

[archangel88]

Agree with C. Think of it like this:
Time = 0 10^4 = 1*10^4
1/6 2*10^4
2/6 4*10^4 = 2^2*10^4
3/6 8*10^4 = 2^3*10^4
4/6 16*10^4 = 2^4*10^4
5/6 32*10^4 = 2^5*10^4
6/6 64*10^4 = 2^6*10^4

[dhiru85]

It's C for me.