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allochka39001 [22]
3 years ago
10

What is the surface area of a sphere with a radius of 21 units

Mathematics
2 answers:
Marrrta [24]3 years ago
7 0

Hope this helps

Answer: 5541.77

natali 33 [55]3 years ago
3 0
  • formulae is 4πr²
  • 4×22/7×21²
  • 4×22×3×21
  • cause 7 divided the first 21 which gave it 3
  • answer=5544cm²
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Shoemakers of America forecasts the following demand for the next six months: 5000 pairs in month 1; 6000 pairs in month 2; 7000
Andrew [12]

Answer:

5,000+6,000+7,000+,9,000+6,000+5,000= 38,000

Step-by-step explanation:

8 0
3 years ago
Pilar is playing with a motorized toy boat. She puts the boat in a lake and it travels 400m at a constant speed. On the way back
ankoles [38]

Answer:

The trip normally takes 8 minutes

Step-by-step explanation:

The given information states that the away distance the boat traveled = 400 m

The time traveled at the same initial  speed , v₁, by the boat on the way back = 2 minutes

The increase in speed of the boat by Pilar =  10 m/min

The new speed, v₂ = v₁ + 10

The time for the return trip, t₂ = 60 seconds (1 minute) faster than time for the trip, t₁

t₂ = t₁ - 1

Therefore we have;

v₁ × t₁ = v₁×2 + v₂×(t₂-2) = 400

v₁×2 + (v₁ + 10)×(t₂-2) = 400

(v₁ + 10)×t₂ - 20 = 400

But v₁ = 400/t₁ = 400/(t₂ + 1)

Which gives;

(400/(t₂ + 1) + 10)×t₂ - 20 = 400

10×(t₂²+ 36·t₂-2)/(t₂+1) = 400

10·t₂²+ 10·t₂-420 = 0

t₂²+ t₂-42 = 0

(t₂ - 7)(t₂ + 6) = 0

t₂ = 7 minutes or -6 minutes

Given that t₂ is a natural number, we have, t₂ = 7 minutes

Whereby, t₂ = t₁ - 1, we have;

7 =  t₁ - 1

t₁ = 1 + 7 = 8 Minutes

The trip normally takes 8 minutes

3 0
3 years ago
Find an expression which represents the difference when (-4x-2) is subtracted from (-8x+3) in simplest terms.
g100num [7]

Answer:

for problem 1: -4 x -2 = -6

for problem 2: -8x +3 = -11x

Step-by-step explanation:

I hope it helped

brainlest please

7 0
2 years ago
Read 2 more answers
A user’s password to access a computer system consists of 3 letters followed by 2 digits. How many different passwords are possi
Vesnalui [34]

Answer:

26*26*26 = 17576 ways to select 3 letters

10*10= 100 ways to select 2 numbers

So then the total number of ways are:

26^3 *10^2 = 1757600 possible ways

Step-by-step explanation:

For this case we assume that we have 26 letters from A to Z and 10 numbers from 0 to 9 .

And we want to calculate the number of possible passwords possible if the password consists of 3 letters followed by 2 digits.

And for this case we can use the multiplication principle of combinatories, since we don't have any restriction about the letters of the numbers we can have repetition of letters or numbers.

For the number of possible letters:

26*26*26 = 17576 ways to select 3 letters

10*10= 100 ways to select 2 numbers

So then the total number of ways are:

26^3 *10^2 = 1757600 possible ways

7 0
3 years ago
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JOSIE HAS 43 ANIMAL BOOKS AND 29 ART BOOKS . SHE PUTS ALL THE BOOKS ON 8 SHELVES . SHE PUTS THE SAME NUMBER OF BOOKS ON EACH SHE
zepelin [54]

Answer:

9 books on each shelf

Step-by-step explanation:

43 + 29 = 72 books total

72/8 = 9 books per shelf

7 0
3 years ago
Read 2 more answers
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