In Australia, the majority of rainfall happens in December to March when we are having our summer. In order to create a "White Christmas", we tear up a piece of paper into tiny pieces, and throw them up in the air.
Assume that we have the Incredible Hulk to help us. He can take any stack of paper, and tear the entire stack into 2, thereby doubling the number of pieces. Starting from a single piece of paper, what is the minimum number of tears that we must do, in order to get at least 1 , 0 0 0 , 0 0 0 , 0 0 0 (really tiny) pieces of paper?
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okay.
i guess worked with my calculator till 30, and at last i got it right
log 1000000000/log2
Hey, min. total no. of tears is 1+2+3+...+30. Not just 30. Why are u not counting the previous tears ?
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You don't count the sum of the tears. It's on the 30th tear that you get at least 1,000,000,000 pieces.
as we keep dividing by 2 it forms a progression 2^n > 10^9
taking log on both sides n * log2 = 9
n = 9/log 2
the corresponding integer value is 30
Sorry, I was wrong!It actually is not.The table was incorrect...
check first before you type
But 2 on the power of 29 is bigger than 1,000,000,000 , so the answer is not true!I checked the powers of 2 table
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Hey! Who said 2^29 .1000000000. 2^29= 536870912.
For x tears, the Incredible Hulk can produce 2 x pieces of paper.
The problem wants us to find the smallest natural value of x such that the inequality 2 x ≥ 1 0 9 holds.
Applying lo g 2 to both sides, we get that x ≥ 9 + 9 × lo g 2 5 . If I know that lo g 1 0 2 ≈ 0 . 3 , we can say that lo g 2 5 ⇒ l o g 1 0 2 l o g 1 0 5 ≈ 0 . 3 0 . 7 = 2 . 3 . Thus, x ≥ 2 9 . 9 ⇒ x = 3 0 .
same method :)
Every time the paper is divided into 2.
so the equation is 2 x = 1 0 0 0 3
3 2 2 = 1 0 2 4
32 happens to be a power of 2
2 1 0 = 1 0 2 4
2 3 0 is obviously about 1 , 0 0 0 , 0 0 0 , 0 0 0
Therefore the paper must be halved 30 times.
the sequence we have is : (1.2.4.8......) "Geometric sequence"
then: a=1
r= 2/1 = 4/2 = 8/4 .....=2
Sum = 1,000,000,000
sum = a(1-r^n / 1-r)
1,000,000,000 = 1x ( 1-2^n / -1) ------> by solving, n = 29.897 = 30
Our equation is two to the x power is greater than 1000000000. First we will solve for what value of x actually gets 1000000000. Let's use our logarithmic properties: x will be equal to log(1000000000) divided by log(2). Well, log(1000000000) just equals 9, so divided by log(2) equals 29.897. The next integer above that is 30.
1 piece of paper when torn will give u 2 pieces.....
hence
1=2^1
2=2^2
3=2^3
...
...
...
...
n=2^n
...given here is total pieces obtained.and we have to find torn we made
hence
2^n=1,000,000,000
taking log on both sides
n* log2=log(1,000,000,000)
.... n * 0.3=9
..... n=9/0.3
n=30
On the first tear, it yields two pieces, on the second it yields 4, one the third it yields 8, and so on. So 2^{n} = (number of pieces)
2^{34} = 1x10^{9}
log {2}(2^{n}) = log {2}1x10^{9}
n = log_{2}1x10^{9}
n ≈ 30
We have to find k such that 2 k > 1 , 0 0 0 , 0 0 0 , 0 0 0 but 2 k − 1 < 1 , 0 0 0 , 0 0 0 , 0 0 0 . So k = 3 0 as lo g 2 ( 1 , 0 0 0 , 0 0 0 , 0 0 0 ) ∼ 2 9 .
Since 2^29<1000000000<2^30
Answer is 30
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Since the Hulk is tearing down the entire stack into 2 , then 4 , then 8 , and so on,
2 x = 1 , 0 0 0 , 0 0 0 , 0 0 0 , where x is the number of times Hulk has to tear the stack into 2 .
2 x = 1 0 0 0 3
Since the power of 2 closest to 1 0 0 0 is 1 0 2 4 ,
2 x is about 1 0 2 4 3
2 x is about ( 2 1 0 ) 3
2 x is about 2 3 0
Therefore, the smallest whole number x that gives 2 x > 1 , 0 0 0 , 0 0 0 , 0 0 0 is 3 0