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.
Answer:
$6
Step-by-step explanation:
$20-$14=$6
Answer:
y = 3x + 1
Step-by-step explanation:
If two lines are parallel to each other, they have the same slope.
The first line is Y = 3X - 5. Its slope is 3. A line parallel to this one will also have a slope of 3.
Plug this value (3) into your standard point-slope equation of y = mx + b.
y = 3x + b
To find b, we want to plug in a value that we know is on this line: in this case, it is (0, 1). Plug in the x and y values into the x and y of the standard equation.
1 = 3(0) + b
To find b, multiply the slope and the input of x (0)
1 = 0 + b
Now, add 0 to both sides to isolate b.
1 = b
Plug this into your standard equation.
y = 3x + 1
This equation is parallel to your given equation (y = 3x - 5) and contains point (0, 1)
Hope this helps!
Answer:
20.39
Step-by-step explanation:
35.99 – 15.6 = 20.39
Answer:
Step-by-step explanation:
1. Null hypothesis: u <= 0.784
Alternative hypothesis: u > 0.784
2. Find the test statistics: z using the one sample proportion test. First we have to find the standard deviation
Using the formula
sd = √[{P (1-P)}/n]
Where P = 0.84 and n = 750
sd =√[{0.84( 1- 0.84)/750]}
sd=√(0.84 (0.16) /750)
SD =√(0.1344/750)
sd = √0.0001792
sd = 0.013
Then using this we can find z
z = (p - P) / sd
z = (0.84-0.784) / 0.013
z =(0.056/0.013)
z = 4.3077
3. Find the p value and use it to make conclusions...
The p value at 0.02 level of significance for a one tailed test with 4.3077 as z score and using a p value calculator is 0.000008254.
4. Conclusions: the results is significant at 0.02 level of significance suck that we can conclude that its on-time arrival rate is now higher than 78.4%.