The exact circumference of the circle is 
The approximate circumference of the circle is 
Explanation:
The diameter of the circle is 
Now, we shall find the circumference of the circle.
The formula to determine the circumference of the circle is given by

Where C is the circumference ,
is 3.14 and
is the diameter of the circle.
The exact circumference of the circle is given by

Multiply both numerator and denominator by 100, we get,

Converting
into mixed fraction, we get,

Thus, the exact circumference of the circle is 
The approximate value of the circumference can be determined by dividing the value 


Thus, the approximate circumference of the circle is 
Answer:
Therefore the required ways are =190
Step-by-step explanation:
Combination: Combination is the number of selection of items from a collection of items where the order of selection does not matter.
Total number of smartphones =22
Defective phone = 2
Non defective phone = (22-2) =20
The control inspector randomly test 4 smartphones of which 2 are defective.
Non defective phone = 2
The ways to select 2 non defective phone is

The ways to select 2 defective phone is= 
Therefore the required ways are = (190×1) =190
-9/ 3= -3
-3 + -4 + -2 = -9
the numbers are -2 , -3 , -4
Answer:

And that represent the probability that they take longer than 7 minutes to solve the puzzles.
Step-by-step explanation:
The complement rule is a theorem that provides a connection between the probability of an event and the probability of the complement of the event. Lat A the event of interest and A' the complement. The rule is defined by: 
On this case we have that n= 56 represent the employees selected to solve the puzzles.
We know that 23 out of the 56 selected solved the puzzles in less than 7 minutes.
Let's define the events A and A' like this:
A: Employees solved puzzles in less than 7 minutes
By the complement rule then:
A' : Employees solved puzzles in more than 7 minutes
Based on this we are interested to find the probability for A'
We can begin finding P(A), from the definition of probability we know:

For this case if we replace we got:

And using the complemnt rule we got:

And solving for P(A') we got:

And that represent the probability that they take longer than 7 minutes to solve the puzzles.