When the balloon is on the ground, it is at point 0. It starts to go up at 5 f/m for a time of 4 minutes. So we will multiply 5 by 4 to get 20. At this point, the balloon is 20 feet off the ground. However, we now know that the balloon descends at 2 f/m at a time of 7 minutes. So we must multiply 2 by 7 to get 14. So we know it was at 20, and then it went down by 14.
20 - 14 = 6 feet
This means that the balloon is now 6 feet above the ground.
I hope I've helped! :)
Answer:
hi
Step-by-step explanation:
x=-3
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:
brainly.com/question/3112062
Answer:
65.45
Step-by-step explanation:
Zscore = (x - mean) / standard deviation
x = score
Percentage below C :
D = 18% ; F = 12%
Sum = 30%
Obtain the Zscore for the proportion below D
P(Z < 0.30) = -0.524
Hence, Zscore = -0.524
Put Zscore = -0.524 in the equation :
-0.524 = (x - 72) / 12.5
-0.524 * 12.5 = x - 72
-6.55 = x - 72
-6.55 + 72 = x
x = 65.45
To receive a grade of C or better, score must be atleast 65.45