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igomit [66]
3 years ago
6

Question 9 (3 points)

Mathematics
1 answer:
Lilit [14]3 years ago
7 0

Answer:

Precambrian period

Step-by-step explanation:

Since the Great oxidation period = 2.4 Billion years ago era = Precambrian period.

Micro-fossils attributed to cyanobacteria are abundant during the Proterozoic that came later 2,5 billion years ago and ended 540 million years ago,

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What is the value of "c" in the quadratic equation 3x 2 + 5x + 7 = 0?
Nutka1998 [239]

Answer:

7

Step-by-step explanation:

The quadratic equation looks like:

ax + by + c = 0

"c" is the variable that stands for the "constant", or the number that does not have an extra variable attached, and so is "unchanging". In this case, your answer is 7, which is the constant of the equation. Once defined, the number cannot be changed.

~

3 0
3 years ago
Read 2 more answers
Plwees help:)
KATRIN_1 [288]

Answer:

Step-by-step explanation:

10 miles in 80 minutes = 1 mile in x minutes

10/80 = 1/x

10x = 80

x = 80/10

x= 8 miles per minute <===

======================

14 lbs rice for $ 8 = 1 lb rice for x $

14/8 = 1/x

14x = 8

x = 8/14

x = 0.57 per lb <=== thats 57 cents per lb

5 0
3 years ago
Two water pumps are filling a pool. One of the pumps is high power and can fill the pool 5 hours before the other can do. Howeve
9966 [12]

L = hours for the slower pump to fill the pool

L - 5 = hours for the high power pump, since it can do it in 5 hours less.

since the slower pump takes L hours, the faster pump takes then L - 5 hours.

we know both pumps together take 3 hours to do <u>half of the pool</u>, so that means that to fill up <u>the whole pool it takes them 6 hours</u>.

since the slower pump can do it alone in L hours, in 1 hour it has done 1/L of the whole thing.

likewise, since the faster pump can do it in L-5 hours, in 1 hour alone it has done 1/(L-5) of the whole job.


\bf \stackrel{\textit{slower pump's rate}}{\cfrac{1}{L}}~~~~+\stackrel{\textit{faster pump's rate}}{\cfrac{1}{L-5}}~~~~=~~~~\stackrel{\textit{total done in 1 hour}}{\cfrac{1}{6}} \\\\\\ \textit{let's multiply both sides by }\stackrel{LCD}{6(L)(L-5)}\textit{ to do away with the denominators} \\\\\\ 6(L)(L-5)\left( \cfrac{1}{L}+\cfrac{1}{L-5} \right)=6(L)(L-5)\left( \cfrac{1}{6} \right)


\bf 6(L-5)+6L=(L)(L-5)\implies 6L-30+6L \\\\\\ 12L-30=L^2-5L\implies 0=L^2-17L+30 \\\\\\ 0=(L-15)(L-2)\implies L= \begin{cases} \boxed{15}\\ 2 \end{cases}


now, we can't use L = 2, because, the whole job by both is done in 6 hours, there's no way the slower pump can do it in less than that, so L = 15.

now if L = 15, then L - 5 = 10.

5 0
4 years ago
There are 10 students in a class: 3 boys and 7 girls. If the teacher picks a group of 3 at random, what is the probability that
Sladkaya [172]
2/3 is the probability
8 0
4 years ago
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Mary McDonald makes mugs in Miami. She makes two sizes of mugs: a small mug that she sells for $2.50 and a large mug that she se
IrinaVladis [17]

Mary McDonald sold 11 small mugs and 10 large mugs.

Step-by-step explanation:

Given,

Total cost of sold cups = $85

Cost of one small cup = $2.50

Cost of one large cup = $5.75

Cups at the start of day = 215

Cups at the end of day = 194

Cups sold = Cups at the start of day - Cups at end of day

Cups sold = 215 - 194 = 21

Let,

x represents the number of small cups.

y represents the number of large cups.

According to given statement;

x+y=21    Eqn 1

2.50x+5.75y=85    Eqn 2

Multiplying Eqn 1 by 2.50

2.50(x+y=21)\\2.50x+2.50y=52.50\ \ \ Eqn\ 3

Subtracting Eqn 3 from Eqn 2

(2.50x+5.75y)-(2.50x+2.50y)=85-52.50\\2.50x+5.75y-2.50x-2.50y=32.50\\3.25y=32.50

Dividing both sides by 3.25

\frac{3.25y}{3.25}=\frac{32.50}{3.25}\\y=10

Putting in Eqn 1

x+10=21\\x=21-10\\x=11

Mary McDonald sold 11 small mugs and 10 large mugs.

Keywords: linear equation, subtraction

Learn more about linear equations at:

  • brainly.com/question/12905000
  • brainly.com/question/12918501

#LearnwithBrainly

7 0
3 years ago
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