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Nady [450]
3 years ago
13

A skateboarder went a kilometer in 3 minutes with the wind, and returned in four minutes against the wind.

Mathematics
1 answer:
inn [45]3 years ago
8 0

Step-by-step answer:

Answer to problems of this kind is the reciprocal of the harmonic mean of the time required.

We need to find the average of the speeds, not the average of the time.

The respective speeds are 1/3 and 1/4.

The average of the speeds is therefore (1/3+1/4)/2 = 7/24  (harmonic mean of the time taken).

The time required is therefore the reciprocal of the unit speed,

T = 1/(7/24) = 24/7 = 3 3/7 minutes, or approximately 3.43 minutes.

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4

let the number be x

so by the question , 2x+5=13

solving this we get ,

2x=13-5

2x=8

so x=4

6 0
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Yakvenalex [24]
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Answer:

Angle ABC is equal to 130.4°

Step-by-step explanation:

When an angle is bisected, it is divided into two equal parts, so if BD bisects ∠ABC, then the two angles that add up to it, ∠ABD and  ∠DBC, must be equivalent.

We know that ∠ABD equals 65.2, so that must mean that ∠DBC also equals 65.2.

Here is our equation:

∠ABC=∠ABD+∠DBC

After substituting, we will get

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3 years ago
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What is equivalent to 2/5
LuckyWell [14K]
There are many answers. I’ll give you three examples...

4/10
6/15
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There is a pattern too, just a trick!
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What is the markup percent on a diamond for which the markup is $870 and the selling price is $2870?
ryzh [129]

Answer:

30.31%

Step-by-step explanation:

Mark up on selling price is given by markup*100%/selling price

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