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3 years ago

What was the average speed in km/h of:

Mathematics

1 answer:

nirvana33 [79]3 years ago

6 0

Answer:

The average speed of the boat is 20 km/hr.

Step-by-step explanation:

Given : A boat that moves 15.0 km across a lake in 45 min.

To find : What was the average speed in km/h ?

Solution :

The distance a boat covered is 15 km.

The time taken by boat to cross a lake is 45 minutes.

Convert minute into hour,

1 hour = 60 minute

1 minute = $\frac{1}{60}$ hour

45 minute = $\frac{45}{60}$ hour

45 minute = 0.75 hour

The speed of the boat is given by,

$\text{Speed}=\frac{\text{Distance}}{\text{Time}}$

$\text{Speed}=\frac{15}{0.75}$

$\text{Speed}=20$

The average speed of the boat is 20 km/hr.

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Simplify completely quantity x squared minus 4 x plus 4 over quantity x squared plus 10 x plus 25 times quantity x plus 5 over q

sukhopar [10]

Haha, this is more a problem of reading the question right :)

(x^2-4x+4)/(x^2+10x+25) * (x+5)/(x^2+3x-10)

Upon factoring the numerator and denominators...

[(x-2)^2/(x+5)^2]*(x+5)/((x+5)(x-2)) so on the right side the (x+5)s cancel

((x-2)^2/(x+5)^2)*1/(x-2) which is:

[(x-2)^2]/[(x+5)^2*(x-2)] now you can see that (x-2)^1 cancels

(x-2)/(x+5)^2 or if you prefer it expanded...

(x-2)/(x^2+10x+25)

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2 years ago

Me Sidney rented a car for a day. The rental fee consists of flat rate of $19.99 plus 0.21 for an additional mile. For how how m

ipn [44]

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3 years ago

mckenna and lara work for their uncle eddie, who repairs skateboards and bicycles. uncle eddie is leaving for a vacation to the

juin [17]

The <em><u>correct answer</u></em> is:

15 bicycles and 6 skateboards.

Explanation:

Let x represent the number of bicycles and y represent the number of skateboards. The first equation in our system is then

x+y = 21, since there are 21 total items in the shop.

Each bicycle has 2 tires and each skateboard has 4; this gives us the equation

2x+4y=54 (because they are ordering 54 tires).

This makes our system

$\left \{ {{x+y=21} \atop {2x+4y=54}} \right.$

We will use elimination to solve this; we first need one of the variables to have the same coefficient in both equations. We will make x the same, and we will do this by multiplying the first equation by 2:

$\left \{ {{2(x+y=21)} \atop {2x+4y=54}} \right. \\
\\\left \{ {{2x+2y=42} \atop {2x+4y=54}} \right.$

Now we will subtract the second equation from the first one:

$\left \{ {{2x+2y=42} \atop {-(2x+4y=54)}} \right. \\
\\-2y=-12$

Divide both sides by -2:

-2y/-2 = -12/-2

y = 6

There were 6 skateboards. Substituting this into the first equation,

x+6 = 21

Subtract 6 from each side:

x+6-6 = 21-6

x = 15

There were 15 bicycles.

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2 years ago

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2 years ago

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Julia is standing 2 feet away from a lamppost. If she casts a shadow of 5 feet and the light makes a 20° angle relative to the g

givi [52]

Answer:

2.5477 feet

Step-by-step explanation:

Refer the image attached to understand my solution.

BC = height of lamppost.

DE = Julia

AD = shadow of Julia

BD = 2 feet. AD = 5 feet

BA = BD + AD

= 2 + 5 = 7 feet

In ΔABC

tan 20° = $\frac{BC}{BA} = \frac{BC}{7}$

BC = 7 * tan 20°

BC = 2.5477 feet

SO the height of lamppost = 2.5477 feet

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2 years ago