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kiruha [24]
2 years ago
12

HIGH POINTS! AND BRAINLY! PLEASE GIVE GOOD AND GENIUNE ANSWERS OR I WILL DELETE YOUR COMMENT AND TAKE THE POINTS BACK:

Mathematics
2 answers:
Margarita [4]2 years ago
7 0

Answer:

r = 28 km/hr

d = 140 km

Step-by-step explanation:

The distance between the two towns is d

We know the formula for distance is d = rt

A biker covered half the distance between two towns in 2 hr 30 min.

Changing the time to hours and calling the rate r

d/2 = r * 2 1/2

For the second part the rate is (r+2)

He covered the second half of the distance in 2 hr 20 min

Changing the time to hours 2 hrs 20 min = 2 1/3 hours

d/2 = (r+2)( 2 1/3)

Since the distances are the same, we can set the two equations equal

r * 2 1/2 = (r+2)( 2 1/3)

Changing to improper fractions

r (5/2) = (r+2) 7/3

Multiplying each side by 6 to clear the fractions

6r (5/2) = (r+2) 7/3*6

15r = (r+2) *14

Distribute

15r = 14r+28

Subtracting 14r from each side

15r-14r = 14r-14r+28

r = 28

Now we want to find the distance

d/2 = r * 2 1/2

d/2 = 28 (5/2)

Multiply each side by 2

d/2*2 = 28 (5/2)*2

d = 28 *5

d = 140

Elena L [17]2 years ago
5 0

Answer:

Distance: 140 km

Initial speed: 28 km/hr

Step-by-step explanation:

D = speed × time

let S be the Intial speed

And D be the half distance

D = S × 2½

D = (S + 2) × 2⅓

(5/2)S = (S + 2) × 7/3

7/3 S - 5/2 S = 14/3

S/6 = 14/3

S = 28 km/hr

D = 5×28/2 = 70

Total distance = 2×70 = 140 km

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Suppose that 10 sophomores, 3 juniors, and 10 seniors are candidates for a prestigious mathematics award of which three will be
faltersainse [42]

Answer:

1771 possible ways

Step-by-step explanation:

In this case, we need to know first how many candidates are in total:

10 + 3 + 10 = 23 candidates in total.

Now, we need to choose 3 of them to receive an award. In this case, we have several scenarios, but as it's an award we can also assume that the order in which the candidates are chosen do not matter, so, the formula to use is the following:

C = m! / n! (m - n)!

Where m is the total candidates and n, is the number of candidates to be chosen. Replacing this data we have:

C = 23! / 3! (23 - 3)!

C = 2.59x10^22 / 6(2.43x10^18)

C = 1771

So we have 1771 ways of choose the candidates.

7 0
2 years ago
Dakota earned ​$15.00 in interest in Account A and ​$22.50 in interest in Account B after 18 months. If the simple interest rate
11111nata11111 [884]

Answer:

Step-by-step explanation:

Dakota kiếm được 15 đô la tiền lãi trong Tài khoản A và 22,50 đô la tiền lãi trong Tài khoản B sau 18 tháng

5 0
2 years ago
Can a triangle with side lengths of 8, 15, and 17 be a right triangle?
Nookie1986 [14]
Yes it is. 
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7 0
3 years ago
Read 2 more answers
What is the answer?​
charle [14.2K]

Answer:

x = 20 but see below.

Step-by-step explanation:

Remark.

This is not well enough marked to know whether D = A or whether you have to do some algebra to find the relationship between A and D. So I will assume A = D and then I'll solve it so you have to manipulate A and D.

A = D

3x - 10 = 2x + 10                     Add 10 to both sides

3x - 10 + 10 = 2x + 10 + 10     Cancel

3x = 2x + 20                           Subtract 2x from both sides

3x-2x=2x-2x + 20

x = 20

A = E

If A = E then to find x you have to add 3 angles together.

E + D + 45 = 180                  Add the three angles of the triangle

E + D = 180 - 45                  Subtract  45 from both sides

E + D = 135                          Substitute for D and E

3x - 10 + 2x + 10 = 135        Combine like terms

5x = 135                              Divide by 5

x = 135 / 5

x = 27

Answer

I'd go with the first one.

5 0
3 years ago
A field bordering a straight stream is to be enclosed. The side bordering the stream is not to be fenced. If 1000 yards of fenci
sveta [45]

Answer:

x  =  500 yd

y  =  250 yd

A(max) = 125000 yd²

Step-by-step explanation:

Let´s call x the side parallel to the stream ( only one side to be fenced )

y the other side of the rectangular area

Then the perimeter of the  rectangle  is  p  =  2*x  + 2* y  ( but only 1 x will be fenced)

p  =  x  +  2*y

1000  =  x   +  2 * y         ⇒    y  =  (1000 - x )/ 2

And   A(r)  =  x * y

Are as fuction of x

A(x)  =  x  *  (  1000  -  x ) / 2

A(x)  =   1000*x / 2 -  x² / 2

A´(x)  =  500  -  2*x/2

A´(x)  =  0              500   -  x   =  0

x  =  500 yd

To find out if this value will bring function A to a maximum value we get the second derivative

C´´(x)  =  -1         C´´(x) < 0  then efectevly we got a maximum at  x  = 500

The side  y  = ( 1000  -  x ) / 2

y  =  500/ 2

y  =  250 yd

A(max)  =  250 * 500

A(max) = 125000 yd²

3 0
2 years ago
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