Here is the equation:

Since both decimals are negative, the answer will be positive.
- Negative times Negative = Positive
Divide both sides by -3.9 to leave the variable alone:

r is equal to 4 → r = 4
Answer:
what do you need?
Step-by-step explanation:
I don't see a question.
There are 2 answers: Choice 1, Choice 4
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Why is this? Because we use the rule
P(A & B) = P(A) * P(B)
which only works if events A and B are independent
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For the first answer choice,
P(A) * P(B) = 0.6*0.4 = 0.24 = P(A & B)
so that matches.
The same applies to the fourth answer choice as well
P(A) * P(B) = 0.3*0.2= 0.06 = P(A & B)
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The other answer choices don't match up.
The second answer choice has
P(A) * P(B) = 0.3*0.4 = 0.12 but that doesn't match with the 0.70 given
Similarly for the third answer choice,
P(A) * P(B) = 0.5*0.1 = 0.05 which doesn't match with the 0.60
Answer:

Step-by-step explanation:
Let:

Substitute for y in equation (b) to equation (a):

Also, y = 0
Answer:
The 99% confidence interval for the mean amount of money spent on lunch per week for all college students is between $41.40 and $44.60.
Step-by-step explanation:
A confidence interval has two bounds, a lower bounds and an upper bound.
These bounds depend on the sample mean and the margin of error.
The lower bound is the sample mean subtracted by the margin of error.
The upper bound is the margin of error added to the sample mean.
In this problem, we have that:
The sample mean is $43.
The margin of error is $1.60 for a 99% confidence interval.
Lower bound: 43 - 1.60 = $41.40
Upper bound: 43 + 1.60 = $44.60
The 99% confidence interval for the mean amount of money spent on lunch per week for all college students is between $41.40 and $44.60.