Mathematics, 03.10.2019 05:30 kellyroy74

Adolphin jumps out of the water with
an initial velocity of 20 feet per second.
the dolphin's height, h, after t seconds
of time can be modeled by the
equation:
h(t) = -16t2 + 20t.
determine how long it took for the
dolphin to return to the water.

Answers: 2

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Answers

Answer from: SKSKSKSKGKUFHjk

$t=1.25\ sec$

Step-by-step explanation:

we have

$h(t)=-16t^{2}+20t$

where

t is the time in seconds

h is the dolphin's height in feet

we know that

When the dolphin return to the water the value of h(t) is equal to zero

For h(t)=0

$0=-16t^{2}+20t$

$16t^{2}=20t$

Simplify

16t=20

$t=\frac{20}{16}$

$t=\frac{5}{4}=1.25\ sec$

see the attached figure to better understand the problem

Adolphin jumps out of the water with an initial velocity of 20 feet per second. the dolphin's height

Answer from: Quest

answer:

total cost for tiles and paints is $924.

step-by-step explanation:

we have been given that a community hall is in the shape of a cuboid. the hall is 40m long 15m high and 3m wide.

the paint will be required for 4 walls and ceiling.

let us find area of walls and ceiling.

$\text{area of walls and ceiling}=(2*40*15)+(2*3*15)+(40*3)$

$\text{area of walls and ceiling}=1200+90+120$

$\text{area of walls and ceiling}=1410$

therefore, the area of walls and ceiling is 1410 square meters.

given: cost for 10 litre of paint is $10 and 10 litre paint covers 25 square meter. therefore,

$\text{ the total painting cost}=10*(\frac{1410}{25})$

$\text{ the total painting cost}=10*56.4=564$

therefore, the total painting cost is $564.

tiles will be required for floor. let us find the area of floor.

$\text{area of floor} = 40*3\text{ square meters}$

$\text{area of floor} =120\text{ square meters}$

given: 1m squared floor tiles costs $3. so,

$\text{total cost for tiles} = 3*120 = 360$

therefore, the total tiles cost is $360.

now let us find combined total cost of tiles and paint.

$\text{combined total cost}= 564+360 = 924$

therefore, the combined total cost of tiles and paint is $924.

Answer from: Quest

irst, find the z score of a score of 80. this is given by the formula z = (x-u)/o, where x is the score, u is the mean, and o is the standard deviation. this gives

z = (80-78)/12 = 1/6 = .1667

now, find what percentile a z score of 1/6 correlates to in the normal distribution.

a z score of 1/6 = .1667 is equivalent to the 56.36th percentile of the distribution. so the probability a score is over this is 1-.5636 = .4364

the mean of a sample mean is equal to the original mean. however, the standard deviation of a sample mean is equal to the original standard deviation divided by the square root of n (sample size). so the new standard deviation is 12/sqrt(16) = 3.

the new z score is 80-78/3 = 2/3 = .667. this is equivalent to the 74.86th percentile. so the probability that the mean will be greater than this score is 1-.7486 = .2514.

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Adolphin jumps out of the water with
an initial velocity of 20 feet per second.
the dolp...

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