Answer:
Step-by-step explanation:
butt
I used the quadratic formula and got x= 4, -6
Answer:
(0.4958, 0.7422)
Step-by-step explanation:
Let p be the true proportion of water specimens that contain detectable levels of lead. The point estimate for p is 
. The estimated standard deviation is given by 
. Because we have a large sample, the 90% confidence interval for p is given by 
where 
is the value that satisfies that above this and under the standard normal density there is an area of 0.05. So, the confidence interval is 
, i.e., (0.4958, 0.7422).
Let x = the amount of grapes that can be bought for 0.40.
Note: By 90 I assume you mean 90 cents. The same for 40.
12/x = 0.90/0.40
0.90x = 12(0.40)
0.90x = 4.80
x = 4.80 ÷ 0.90
x = 5.33333
We can round the decimal to the ones place to get 5 grapes.
