So we need to represent the problem using an equation
900 = the original pile of bricks (x) + 25% more - 40% (original + 25% extra)
900 = x + .25x - .4(x + x*.25)
900 = x + .25x - .4x - .1x
900 = .75x
x = 1200
Answer:
Depending on how they grade..... a D or a C-
Step-by-step explanation:
Step-by-step explanation:
area = ( base 1 + base 2 ) ÷ 2 x height
50 = ( 10 + 15) ÷2 x height
50 ÷ 12.5 = height
height = 4
Before winter, apples used to cost $1.21 per pound, now they cost $1.96 per pound.
Answer:
Margin of error at 90% is 0.024
Margin of error at 99% is 0.037
Step-by-step explanation:
Sample size = 1076
A poll found that 64% of a random sample of 1076 adults said they believe in ghosts.
So, No. of adults said they believe ghosts = ![\frac{64}{100} \times 1076=688.64\sim 688](https://tex.z-dn.net/?f=%5Cfrac%7B64%7D%7B100%7D%20%5Ctimes%201076%3D688.64%5Csim%20688)
So, x = 688
n = 1076
![\widehat{p} = \frac{x}{n}](https://tex.z-dn.net/?f=%5Cwidehat%7Bp%7D%20%3D%20%5Cfrac%7Bx%7D%7Bn%7D)
![\widehat{p} = \frac{688}{1076}](https://tex.z-dn.net/?f=%5Cwidehat%7Bp%7D%20%3D%20%5Cfrac%7B688%7D%7B1076%7D)
![\widehat{p} = 0.639](https://tex.z-dn.net/?f=%5Cwidehat%7Bp%7D%20%3D%200.639)
![ME=z \times \sqrt{\frac{\widehat{p}(1-\widehat{p})}{n}}](https://tex.z-dn.net/?f=ME%3Dz%20%5Ctimes%20%5Csqrt%7B%5Cfrac%7B%5Cwidehat%7Bp%7D%281-%5Cwidehat%7Bp%7D%29%7D%7Bn%7D%7D)
z at 90% confidence is 1.64
![ME=1.64 \times \sqrt{\frac{0.639(1-0.639)}{1076}}](https://tex.z-dn.net/?f=ME%3D1.64%20%5Ctimes%20%5Csqrt%7B%5Cfrac%7B0.639%281-0.639%29%7D%7B1076%7D%7D)
![ME=0.024](https://tex.z-dn.net/?f=ME%3D0.024)
So, margin of error at 90% is 0.024
Find the margin of error needed to be 99% confident.
z at 99% confidence is 2.58
![ME=2.58 \times \sqrt{\frac{0.639(1-0.639)}{1076}}](https://tex.z-dn.net/?f=ME%3D2.58%20%5Ctimes%20%5Csqrt%7B%5Cfrac%7B0.639%281-0.639%29%7D%7B1076%7D%7D)
![ME=0.024](https://tex.z-dn.net/?f=ME%3D0.024)
So, margin of error at 99% is 0.037