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2 years ago

Tara needs to read for a total of 60 minutes over 3 nights. She will read the same amount of time each night.

Mathematics

1 answer:

Ierofanga [76]2 years ago

3 0

Answer:

A. 20 x 3

Step-by-step explanation:

the amounts of time studied should be the amount studied per day multiplied by the total amount studied in three days, ie 20 minutes per day multiplied by the number of day , which is three days,

this amounts to 60 minutes

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2 years ago

Solve the equation, round number the the nearest hundredth if needed.

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3 years ago

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Answer:

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Step-by-step explanation:

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3 years ago

) The density of oil in a circular oil slick on the surface of the ocean at a distance of r meters from the center of the slick

Feliz [49]

Answer:

Therefore the mass of the of the oil is 409.59 kg.

Step-by-step explanation:

Let us consider a circular disk. The inner radius of the disk be r and the outer diameter of the disk be (r+Δr).

The area of the disk

=The area of the outer circle - The area of the inner circle

= $\pi (r+\triangle r)^2- \pi r^2$

$=\pi [r^2+2r\triangle r+(\triangle r)^2-r^2]$

$=\pi [2r\triangle r+(\triangle r)^2]$

Since (Δr)² is very small, So it is ignorable.

∴ $A=2\pi r\triangle r$

The density $\delta (r)= \frac{40}{1+r^2}$

We know,

Mass= Area× density

$=(2r \pi \triangle r)(\frac{40}{1+r^2}})$

Total mass $M=\sum_{i=1}^n \frac{80r_i\pi }{1+r^2}\triangle r_i$

Therefore

$\sum_{i=1}^n \frac{80r_i\pi }{1+r^2}\triangle r_i=\int_0^5 \frac{80r\pi }{1+r^2}dr$

$=40\pi[ln(1+r^2)]_0^5$

$=40\pi [ln(1+5^2)-ln(1+0^2)]$

$=40\pi ln(26)$

= 409.59 kg (approx)

Therefore the mass of the of the oil is 409.59 kg.

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2 years ago

15. Challenge! Find the surface area of the figure below.

Eduardwww [97]

Is it 25 cm???????.................

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3 years ago