To solve for the time it takes to travel a certain distance at a certain speed, use the formula,
time = distance / speed
Given that the entire journey takes four hours, add up the time it takes David to row upstream with that of him travelling downstream. This is mathematically represented as,
total time = time upstream + time downstream
4 = 3/(x - 1) + 3/(x +1)
Solving for x in the equation gives 2. Thus, David's speed in still water is 2 miles per hour.
1. -35x+710 = -25x+570
-10x=-140
x=14
In 14 weeks, Pedro and Maria's accounts will have the same amount.
2. 9x+90 = 13x+50
-4x=-40
x=10
For 10 square yards of carpeting will the cost be the same for both stores.
3. 0.06x+44 = 0.09x+35
-0.09x= -9
x=100
For 100 miles both companies will charge the same price.
4. 15x+250 = 20x+200
-5x= -50
x= 10
It will take 10 weeks for the amount in each savings account to be the same.
5. 25x+250 = 50x
-25x = -250
x = 10
10 stereos must be sold to make the same amount of money under both plans.
Hope this helps!
<h2>
Answer with explanation:</h2>
Let
be the average weight of chocolate chips in each bag.
As per given , we have

Since
is left-tailed , so we perform a left-tailed test.
Also, the population standard deviation is known
.
So we use z-test.
Test statistic : 
Substitute given value ,

Significance level = 0.05
Decision rule : Reject
when p-value < 0.05.
By z-table , P- value for left-tailed test = P(z<-1.96)= 1- P(z<1.96)
[∵ P(Z<-z)=1-P(Z<z)]
= 1- 0.9750
=0.025
Since , P-value(0.025) < 0.05 , so we reject the null hypothesis.
We support the claim that the machine is underfilling the bags at 0.05 significance level .