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zlopas [31]
2 years ago
15

a boat is going 144 miles upstream on a river. the speed of the boat in still water is 60 miles per hour. the speed of the river

current is 80% less than the speed of the boat in still water. how long does the journey take?( in hours)
Mathematics
1 answer:
Katena32 [7]2 years ago
5 0

Answer:

Let  b  =  rate of the boat.

Let  r  =  rate of the river.

The rate going downstream is  b + r.

The rate going upstream is  b - r.

rate x time  =  distance

4(b + r)  =  144     --->     b + r  =  36     [divide both sides by 4]

9(b - r)  =  144      --->     b - r  =  16      [divide both sides by 9]

Add town:                          2b  =  52  

Divide by :                           b  =  26  mi/hr

                                           r  =  10  mi/hr

Step-by-step explanation:

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Let X be a random variable that is equal to the number of times a 5 is rolled in three rolls of a fair 5-sided die with the inte
Svetradugi [14.3K]

Answer:

Step-by-step explanation:

Note: If you have any queries related the answer please do comment. I would be very happy to resolve all your queries.

Firstly we will make PMF

For X=0, P=(4/5)^3=64/125

For X=1, P=C(3,1)*(1/5)*(4/5)^2=3*16/125=48/125

For X=2, P=C(3,2)*(1/5)^2*(4/5)=3*4/125=12/125

For X=3, P=C(3,3)*(1/5)^3=1/125

So,

E[X^2]=1*48/125+2^2*(12/125)+3^2/125=0.84

E[X]=48/125+12/125*2+1/125*3=0.6

So,

E[X]^2=0.36

7 0
3 years ago
Somebody plz me on this real quick
Kay [80]
I think it would be the second one
4 0
3 years ago
Andrew bought a house worth 200,000 dollars the house value appreciates 1% per year which of the following would help you find t
Aleks [24]

Answer: Option 1:

y=200,000(1.01)exponent 20

Step-by-step explanation:

The house value appreciates 1% per year. It means that the rate at which it is appreciating is exponential. We would apply the formula for exponential growth which is expressed as

y = b(1 + r)^ t

Where

y represents the value of the house after t years.

t represents the number of years.

b represents the initial value of the house.

r represents rate of growth.

From the information given,

b = 200,000 dollars

r = 1% = 1/100 = 0.01

t = 20 years

Therefore,

y = 200000(1 + 0.01)^20

y = 200000(1.01)^20

7 0
3 years ago
You earn $48 for washing 6 cars. How much money do you earn for washing 3 cars
Ghella [55]

Answer: $24

Step-by-step explanation: 3 is half of 6 and if you gain $48 for washing 6 cars then half it half of 6 is 3 and half of $48 is $24

4 0
3 years ago
Coffee beans worth $ 10.50 $10.50 per pound are to be mixed with coffee beans worth $ 13.00 $13.00 per pound to make 50 50 pound
MAVERICK [17]

Answer: 30 pounds of coffee beans worth $10.50 per pound was used.

20 pounds of coffee beans worth $13.00 per pound was used.

Step-by-step explanation:

Let x represent the number of coffee beans worth $10.50 per pound that should be mixed.

Let y represent the number of coffee beans worth $13.00 per pound that should be mixed.

50 pounds of beans worth $11.50 per pound is to be made. The total cost of the mixture would be

50 × 11.5 = 575

This means that

10.5x + 13y = 575 - - - - - - - 1

The total number of pounds of each type of coffee used is 50. This means that

x + y = 50

Substituting x = 50 - y into equation 1, it becomes.

10.5(50 - y) + 13y = 575

525 - 10.5y + 13y = 575

- 10.5y + 13y = 575 - 525

2.5y = 50

y = 50/2.5 = 20

x = 50 - 20= 30

6 0
3 years ago
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