The perimeter of a square is 56cm. What is the approximate length of its diagonal?
2 answers:
Answer:
17.8 cm is the approximate length of its diagonal.
Step-by-step explanation:
Side of the square = l
Perimeter of the square = P = 56 cm
Perimeter of the square is the sum of all the sides of the square.
4a = 56 cm
The length of the diagonal is given by: d
(Pythagoras theorem)
17.8 cm is the approximate length of its diagonal.
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Answer:
85.31% probability that their mean rebuild time exceeds 8.1 hours.
Step-by-step explanation:
To solve this question, we need to understand the normal probability distribution and the central limit theorem.
Normal probability distribution:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean and standard deviation
, the zscore of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
Central limit theorem:
The Central Limit Theorem estabilishes that, for a random variable X, with mean and standard deviation
, the sample means with size n of at least 30 can be approximated to a normal distribution with mean
and standard deviation
In this problem, we have that:
If 40 mechanics are randomly selected, find the probability that their mean rebuild time exceeds 8.1 hours.
This is 1 subtracted by the pvalue of Z when X = 8.1. So
By the Central Limit Theorem
has a pvalue of 0.1469
1 - 0.1469 = 0.8531
85.31% probability that their mean rebuild time exceeds 8.1 hours.
Answer:
28.27 cm/s
Step-by-step explanation:
Though Process:
- The punch glass (call it bowl to have a shape in mind) is in the shape of a hemisphere
- the radius
- Punch is being poured into the bowl
- The height at which the punch is increasing in the bowl is
- the exposed area is a circle, (since the bowl is a hemisphere)
- the radius of this circle can be written as
- what is being asked is the rate of change of the exposed area when the height
- the rate of change of exposed area can be written as
.
- since the exposed area is changing with respect to the height of punch. We can use the chain rule:
- and since
the chain rule above can simplified to
-- we can call this Eq(1)
Solution:
the area of the exposed circle is
the rate of change of this area can be, (using chain rule)
we can call this Eq(2)
what we are really concerned about is how changes as the punch is being poured into the bowl i.e
So we need another formula: Using the property of hemispheres and pythagoras theorem, we can use:
and rearrage the formula so that a is the subject:
now we can derivate a with respect to h to get
simplify
we can put this in Eq(1) in place of
and since we know
and now we use substitute this . in Eq(2)
simplify,
This is the rate of change of area, this is being asked in the quesiton!
Finally, we can put our known values:
from the question
