Answer:
a) the common difference is 20
b) 
c) the common difference is -13
d) 
Step-by-step explanation:
a) what is the common difference of the sequence xn
Looking at the table, we get x_3=16, x_4=36 and x_5= 56
Deterring the common difference by subtracting x_4 from x_3 we get
36-16 =20
So, the common difference is 20
b) what is x_8? what is x_12
The formula used is: 
We know common difference d= 20, we need to find 
Using
we can find 

So, We have 
Now finding 

So, 
Now finding 

So, 
c) what is the common difference of the sequence 
Looking at the table, we get a_7=104, a_8=91 and a_9= 78
Deterring the common difference by subtracting a_7 from a_8 we get
91-104 =-13
So, the common difference is -13
d) what is a_12? what is a_15?
The formula used is: 
We know common difference d= -13, we need to find 
Using
we can find 

So, We have 
Now finding
, put n=12

So, 
Now finding
, put n=15

So, 
In 7500 iPhones, 18 were found defective.
18 of 7500 is 0.24%
0.24% of iPhones were defective.
Using the information above:
In a sample of 60000 new iPhones, 144 would be found defective.
144 of 60000 is 0.24%
Answer: 144 defective iPhones would be expected in a sample of 60,000.
Hope this helps! Good luck. :-)
Hello there!
To find the GCF, we must list all the factors and then just spot the greatest factor.
28: 1, 2, 4, 7, 14, 28.
210 1, 2, 3, 5, 6, 7, 10, 14, 15, 21, 30, 35, 42, 70.
So 14 is the GCF. Hope this helps you!
~Just a felicitous girlie
#HaveAnAwesomeDay
