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, 
Answer:
¼
Step-by-step explanation:
The probability of having a boy is ½ and that of a girl is ½.
Probability of boy, boy is (pb*pb) and given pb to be ½ then we can prove the point as follows
For these two children
The options are as follows
1 boy(first) and 1 girl
2 boys
2 girls
1 girl( first) and 1 boy
These are four possible options and the option for two boys is 1 out of the four.
The probability of 2 boys is ½*½=¼
Wen you deduct an amount from something
2.64575131106 I don’t know if you need to round the answer or not
First find a common denominator and combine the fractions in the numerator:

Now simplify and cancel out all the terms that you can:

Since the remaining expression is continuous as a function of

, you can directly substitute to end up with