The answer is C. 7 x ( 2 x 2 )
Answer:
The mean number of adults who would have bank savings accounts is 32.
Step-by-step explanation:
For each adult surveyed, there are only two possible outcomes. Either they have bank savings accounts, or they do not. So we use the binomial probability distribution to solve this problem.
Binomial probability distribution
Probability of exactly x sucesses on n repeated trials, with p probability.
The expected value of the binomial distribution is:
![E(X) = np](https://tex.z-dn.net/?f=E%28X%29%20%3D%20np)
In this problem, we have that:
![p = 0.64](https://tex.z-dn.net/?f=p%20%3D%200.64)
If we were to survey 50 randomly selected adults, find the mean number of adults who would have bank savings accounts.
This is E(X) when
.
So
![E(X) = np = 50*0.64 = 32](https://tex.z-dn.net/?f=E%28X%29%20%3D%20np%20%3D%2050%2A0.64%20%3D%2032)
The mean number of adults who would have bank savings accounts is 32.
Answer:
It will take 146 days to earn an interest of $80.
Step-by-step explanation:
The simple interest formula is:
![I=\frac{P\times r\times t}{100}](https://tex.z-dn.net/?f=I%3D%5Cfrac%7BP%5Ctimes%20r%5Ctimes%20t%7D%7B100%7D)
It is provided that:
I = $80
P = $4,000
r = 5% p.a.
Compute the time required as follows:
![I=\frac{P\times r\times t}{100}](https://tex.z-dn.net/?f=I%3D%5Cfrac%7BP%5Ctimes%20r%5Ctimes%20t%7D%7B100%7D)
![t=\frac{I\times 100}{P\times r}](https://tex.z-dn.net/?f=t%3D%5Cfrac%7BI%5Ctimes%20100%7D%7BP%5Ctimes%20r%7D)
![=\frac{80\times 100}{4000\times 5}\\\\=0.4\ \years\\\\=0.4\times 365\ days\\\\=146\ days](https://tex.z-dn.net/?f=%3D%5Cfrac%7B80%5Ctimes%20100%7D%7B4000%5Ctimes%205%7D%5C%5C%5C%5C%3D0.4%5C%20%5Cyears%5C%5C%5C%5C%3D0.4%5Ctimes%20365%5C%20days%5C%5C%5C%5C%3D146%5C%20days)
Thus, it will take 146 days to earn an interest of $80.
<span>188.3 </span>÷<span> 7 then...
multiply by 5 = 134.5
so...
Bob drove 134.5 miles or 5/7 of the total distance.</span>
18 kg of 15% copper and 72 kg of 60% copper should be combined by the metalworker to create 90 kg of 51% copper alloy.
<u>Step-by-step explanation:</u>
Let x = kg of 15% copper alloy
Let y = kg of 60% copper alloy
Since we need to create 90 kg of alloy we know:
x + y = 90
51% of 90 kg = 45.9 kg of copper
So we're interested in creating 45.9 kg of copper
We need some amount of 15% copper and some amount of 60% copper to create 45.9 kg of copper:
0.15x + 0.60y = 45.9
but
x + y = 90
x= 90 - y
substituting that value in for x
0.15(90 - y) + 0.60y = 45.9
13.5 - 0.15y + 0.60y = 45.9
0.45y = 32.4
y = 72
Substituting this y value to solve for x gives:
x + y = 90
x= 90-72
x=18
Therefore, in order to create 90kg of 51% alloy, we'd need 18 kg of 15% copper and 72 kg of 60% copper.