Problem 4
c = speed of current
p = paddling speed in still water
Against current:
speed = p-c (start with paddling speed and subtract off current's speed)
speed = 2 (given)
p-c = 2
p = 2+c
With the current
speed = p+c (now the current is speeding things up, so we add on c)
speed = 3 (given)
p+c = 3
2+c+c = 3 ... plug in p = 2+c; solve for c
2+2c = 3
2+2c-2 = 3-2
2c = 1
c = 1/2
c = 0.5
Since c = 0.5, we can use this to find p
p = 2+c
p = 2+0.5
p = 2.5
So,
The speed of the river current is 0.5 mph
Rita's paddling speed in still water is 2.5 mph
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Problem 5
Terms to know:
headwind = wind that slows the plane down (wind is coming from the head of the plane flowing in the opposite direction of the plane's intended direction)
tailwind = wind that speeds the plane up (wind is coming from the tail of the plane flowing in the same direction of the plane's intended direction)
d = distance = 255 miles
p = speed of plane in still air
w = speed of wind
Against the wind (headwind), the plane travels 1.7 hours at some speed p-w. We start with the plane's speed in still air (p) and subtract off the wind speed because the wind is slowing the plane down. So the first equation is
(p-w)*1.7 = 255
since the plane travels 255 miles
I'm using the formula d = r*t
d = distance
r = rate or speed
t = time
Divide both sides of (p-w)*1.7 = 255 by 1.7 and we get p-w = 150
Then add w to both sides and we have p = 150+w
Similarly, the second equation is
(p+w)*1.5 = 255
since the tailwind speeds the plane up from p to p+w, the time is 1.5 hrs and the distance is the same (255 mi)
Plug the equation p = 150+w into the second equation
(p+w)*1.5 = 255
(150+w+w)*1.5 = 255
(150+2w)*1.5 = 255
150*1.5+2w*1.5 = 255
225+3w = 255
225+3w-225 = 255-225
3w = 30
3w/3 = 30/3
w = 10
Use w = 10 to find p
p = 150+w
p = 150+10
p = 160
So,
wind speed = 10 mph
speed of plane in still air = 160 mph
Step-by-step explanation:
(2³ × 2¹)²
(2⁶ × 2²)
for indices , × become +, plus
÷ become -, minus
so
2⁶+²
2⁸
Is this statement true or false?
Fitness levels can be measured by simple tests, such as counting the number of crunches you can do in two minutes.
PEMDAS order refers to parentheses, exponents, multiplication, division, addition, and subtraction. So, 2*5=10 and 34+10=44.
5x -15 + 3 -8x = 13
5x -12 -8x = 13
5x -8x =13 -12
-3x = 1
x = -1/3
