Answer:
A.600
B.980
C.350
D.210
Step-by-step explanation:
just see what the arrow
Answer: -5
Step-by-step explanation: The common difference is the same number we are adding each time to get from one term to the next.
In this sequence, we are adding -5 each time
so our common difference is -5.
Answer:
1. 
2. 
Step-by-step explanation:
Given
Variation: inverse Proportion
y = 7, x = 9
Required
- Write an equation connecting y and x
- Find y when x = 21
Given that thee variation is inversely proportional;
This implies that

Convert variation to equation
----------- Equation 1
Where k is the constant of variation
Substitute 7 for y and 9 for x in equation 1

Multiply both sides by 9


Substitute 63 for k in equation 1

Multiply both sides by x


Hence, the equation connecting x and y is 
Solving for when x = 21
Substitute 21 for x in the above equation

Divide both sides by 21


Answer: 1. 0.0256
2. 0.4096
Step-by-step explanation:
Binomial probability formula , to find the probability of getting x successes:
, where n= Total number of trials
p= Probability of getting success in each trial.
Let x be the number of customers will make purchase.
As per given , we have
p= 0.20
n= 4
1. The probability that 3 of the next 4 customers will make a purchase will be:-

![P(x=3)=(4)(0.20)^3(0.80)^{1}\ \ [\because\ ^nC_{n-1}=n]](https://tex.z-dn.net/?f=P%28x%3D3%29%3D%284%29%280.20%29%5E3%280.80%29%5E%7B1%7D%5C%20%5C%20%5B%5Cbecause%5C%20%5EnC_%7Bn-1%7D%3Dn%5D)

Hence, the probability that 3 of the next 4 customers will make a purchase = 0.0256
2. The probability that none of the next 4 customers will make a purchase will be :

![P(x=0)=(1)(0.80)^{4}\ \ [\because\ ^nC_{0}=1]](https://tex.z-dn.net/?f=P%28x%3D0%29%3D%281%29%280.80%29%5E%7B4%7D%5C%20%5C%20%5B%5Cbecause%5C%20%5EnC_%7B0%7D%3D1%5D)

Hence, the probability that none of the next 4 customers will make a purchase= 0.4096