Scientific notation is used so that the order of the number is known in first glance. The value of the given number in scientific notation is given by: Option B: 
<h3>How does scientific notations work?</h3>
The number is written in the form
where we have 
The number b shows the order, which is the most important figure for which scientific notation is used. It tells us how much order large or small a value is in powers of 10. We can for a time, ignore the value of 'a' for two comparable quantities and only compare their orders(this type of comparison is useful when difference is too big, like size of human to size of a star etc sort of comparisons).
Scientific notations have some of the profits as:
- Better readability due to compact representation
- Its value in terms of power of 10 is known, which helps in easy comparison of quantities differing by a large value.
For the given case, the number in consideration is 0.0000069
Rewriting it in fraction form, we get:

(we used two facts: first that : 
and second that: 
Thus, the value of the given number in scientific notation is given by: Option B: 
Learn more about scientific notations here:
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Answer:
Expected time is 15 hours for him to get to safety.
Step-by-step explanation:
We define X as the time that this miner would get to safety.
We define Y as the door he chooses initially.
P(Y= 1) = P(Y=2)=P(Y=3) = 1/3
We have E[X|Y=1] = 3
E[X|Y] = 5 hours + E[X}
E[X|Y] = 7 hours + E[X]
Then we have
E[X] = 1/3(3 + 5 + E[X] + 7 + E[X])
We cross multiply
3*E[X] = (15 + 2E[x])
3E[X] - 2E[X] = 15
E[X] = 15
So the time it would take to get him to safety is 15 hours
Answer:
He would need to walk the dog 6 more times because 8 times 11 is 88 and if he has already walked the dog 5 times you would subtract that from 11 to get 6. So the answer would be 6
Step-by-step explanation:
8·11= 88
11-5= 6
Answer:
The car must have a speed of 25 kilometres per hour to stop after moving 7 metres.
Step-by-step explanation:
Let be
, where
is the stopping distance measured in metres and
is the speed measured in kilometres per hour. The second-order polynomial is drawn with the help of a graphing tool and whose outcome is presented below as attachment.
The procedure to find the speed related to the given stopping distance is described below:
1) Construct the graph of
.
2) Add the function
.
3) The point of intersection between both curves contains the speed related to given stopping distance.
In consequence, the car must have a speed of 25 kilometres per hour to stop after moving 7 metres.