Mathematics, 27.11.2019 04:31 terry94

Jane took 20 min to drive her boat upstream to water-ski at her favorite spot. coming back later in the day at the same boat speed took her 10 min. if the current in that part of the river is 4 km per hr, what was her boat speed in still water?

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Answer from: jenah6114

12 km/hour

Step-by-step explanation:

Given information: The current in that part of the river is 4 km per hr.

Speed of current = 4 km per hour

Let x be the speed of boat in still water.

Speed of boat in upstream = x-4 km per hour

Speed of boat in downstream = x+4 km per hour

Assume that the distance between Jane's initial position and Jane's favorite spot is D.

Jane took 20 min to drive her boat upstream to water-ski at her favorite spot.

$Distance=Speed\times Time$

For upstream,

$Distance=(x-4)\times 20$

Distance=20x-80 .... (1)

For downstream,

$Distance=(x+4)\times 10$

Distance=10x+40 ..... (2)

Equate (1) and (2) we get

20x-80=10x+40

Isolate variable terms.

20x-10x=80+40

10x=120

Divide both sides by 10.

x=12

The value of x is 12. Therefore, the speed of boat in still water is 12 km/hour.

Answer from: Quest

step-by-step explanation:

i found the life tables for the year 2012.

life table of males at age 30. probability of dying between ages x and x+1

total population:

29–30 . . . . . . . . . . . . 0.001030

30–31 . . . . . . . . . . . . 0.001061

males:

29–30 . . . . . . . . . . . . 0.001420

30–31 . . . . . . . . . . . . 0.001448

white population

29–30 . . . . . . . . . . . . 0.001005

30–31 . . . . . . . . . . . . 0.001037

white males

29–30 . . . . . . . . . . . . 0.001372

30–31 . . . . . . . . . . . . 0.001399

non hispanic white population

29–30 . . . . . . . . . . . . 0.001083

30–31 . . . . . . . . . . . . 0.001116

non hispanic white males

29–30 . . . . . . . . . . . . 0.001477

30–31 . . . . . . . . . . . . 0.001503

jacob, non hispanic white male. 30 years old.

probability that jacob lives to be 30 years old.

since the given probabilities are probabilities of dying, i think we simply subtract it from 1 to get the probability of living. we will use the probability of non hispanic white male.

probability of living to be 30 y.o.

29 - 30 : 1 - 0.001477 = 0.998523

30 - 31 : 1 - 0.001503 = 0.998497

Answer from: Quest

Idon’t have want a lot more

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