A) The first step needs 100 bricks, the second needs 98, the third needs 96, and so on. Therefore the number of bricks for the nth step is: a_n = a_1 + d(n-1), where a_1 = 100 (the first term), d = -2 (difference).
a_n = 100 - 2(n-1) = 102 - 2n, and for the 30th step, a_30 = 102 - 2*30 = 42. So the top step will need 42 bricks.
b) The total staircase will need: 100 + 98 + 96 + ... + 44 + 42, and there are n = 30 terms. Using the formula for the sum of an arithmetic sequence:
S = (a_1 + a_n)*n/2 = (100 + 42)*30/2 = 2130
Therefore, 2130 bricks are required to build the entire staircase.
The number of matinee movies attended is 4.
The number of a evening show movies attended is 2.
<u>Step-by-step explanation:</u>
- Let x represent the number of matinee movies attended.
- Let y represent the number of evening show movies attended.
- Alejandro went to see a total of 6 movies.
Therefore, from the given data the equation can be framed as :
⇒ x + y = 6 ----------(1)
- The cost of a matinee is $7.
- The cost of an evening show is $12.
- Alejandro spent a total of $52.
Therefore, from the given data the equation can be framed as :
⇒ 7x + `12y = 52 ---------(2)
<u>To solve the equations for x and y values :</u>
Mulitply eq (1) and by 7 and subtract eq (2) from eq (1),
7x + 7y = 42
- <u>(7x + 12y = 52)</u>
<u> - 5y = - 10 </u>
⇒ y = 10/5
⇒ y = 2
The number of a evening show movies attended is 2.
Substitute y=2 in eq (1),
⇒ x+2 = 6
⇒ x = 6-2
⇒ x = 4
The number of matinee movies attended is 4.
Answer:
atleast 385
Step-by-step explanation:
Given that an electrical power company is looking to expand into a new market. Before they commit to supplying the new area with electricity, they would like know the mean daily power usage for homes there.
Population std deviation = 
Sample size =
STd error of sample mean = 
Margin of error for 95% would be Critical value ( std error)
Here since population std dev is known we can use Z critical value= 1.96
Sample size should be atleast 385
Answer: 12.9
Step-by-step explanation: When any number is in parenthesis, you multiply it by the other numbers/variables.
