What percent of 80 is 20
1 answer:
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Answer:
401
Step-by-step explanation:
1. Approach
To solve this problem, one first has to think about the given figure in a certain way. In the figure, one can see that it is a circle attached on either side of a rectangle. To find the perimeter of the figure, one has to find the circumference of the circle and then add two sides of the rectangle to the answer
2. Circumference of the circle
The formula to find the circumference of a circle is;
(pi) or
(pi)
~ diameter times the value (pi)
Normally to find the circumference of a semicircle, one would have to divide this formula by 2, but since in this case, one has to add two congruent semicircles, so therefore, the effect of dividing the equation by two, only to multiply by two again cancels, and hence, there is no need to divide by 2.
Substitute in the values;
(78)(pi)
~ 245
3. Find the perimeter of the entire object
Now, one has to add the two additional sides of the figure, to the circumferences of the semicircles to get the final answer;
78 + 78 + 245
= 401
Answer:
192
Step-by-step explanation:
To find how many phones are expected to be defective, we need to represent the values in a fraction.
x = number of defective phones
Now we can solve this using algebra.
To get the value of x we need to multiply both sides by 8000 to leave x alone.
So around 192 cell phones are expected to be defective out of 8000 phones.