Answer: 1692
Step-by-step explanation:
Formula to find the sample size :

Given : Confidence level : 
⇒ significance level =
z-value for 90% confidence interval (using z-table)=
Prior estimate of the population proportion (p) of customers who keep up with regular vehicle maintenance is unknown.
Let we take p= 0.5
Margin of error : E= 2%=0.02
Now, the required sample size will be :

Simplify , we get

Hence, the required sample size = 1692
Answer:
Plates are 2.80 Dollars and cups are 1.40 dollars
Step-by-step explanation:
Cups = c
Plates = p
6p + 5c = 23.80 ==> multiply by 6 ==> 36p + 30c = 142.80
7p + 6c = 28.00 ==> multiply by 5 ==> 35p + 30c = 140.00
Now use algebra to have the 30c be on one side and the rest on the other:
36p + 30c = 142.80 | -36p
30c = 142.80 - 36p
35p + 30c = 140.00 | -35p
30c = 140.00 - 35p
Now set them equal to each other about the 30c:
142.80 - 36p = 140.00 - 35p
Use algebra to solve for p:
142.80 - 36p = 140.00 - 35p | +36p
142.80 = 140.00 + p | - 140
2.80 = p
Go back to one of the "30c" equations and plug in the value for p:
30c = 140 - 35p
30c = 140 - 35(2.80)
30c = 140 - 98
30c = 42 | /30
c = 42/30
c = 1.4
Answer:
option A
Step-by-step explanation:

Answer:
7x+72xy
Step-by-step explanation:
7x+8x(9y)=7x+72xy