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3 years ago

6

A science class has 5 girls and 5 boys in the seventh grade and 3 girls and 5 boys in the eighth grade. The teacher randomly sel

ects a seventh grader and an eighth grader from the class for a competition. What is the probability that the students she selects are both boys? Write your answer as a fraction in simplest form.

2 answers:

kogti [31]3 years ago

7 0

Sample space of 7th grade (5 boys + 5 girls)

sample space of 8th grade (5 boys + 3 girls)

P(boy 7th grade) = 5/10 =1/2
P(boy 8th grade) = 5/8
Hence the probability of selecting a boy from 7th AND a boy from 8th is:

(1/2)x(5/8) ==> 5/16 ( It's a conditional probability)

alexgriva [62]3 years ago

3 0

So the ratios are 5:5 and 3:5 so the fractions are 5/10 (1/2) for 7th grade and 5/8 for 8th grade

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3 years ago

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3 years ago

Oil is pumped continuously from a well at a rate proportional to the amount of oil left in the well. Initially there were millio

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Step-by-step explanation:

Given

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To do this, we make use of the following notations

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$A = Ce^{kt}$

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$A = Ce^{kt}$

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Take natural logarithm (ln) of both sides

$ln(0.5) = ln(e^{k*6})$

$ln(0.5) = k*6$

Solve for k

$k = \frac{ln(0.5)}{6}$

$k = \frac{-0.693}{6}$

$k = -0.1155$

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So, when

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The rate is:

$\frac{dA}{dt} = -0.1155 * 600000$

$\frac{dA}{dt} = -69300$

<em>Hence, the amount of oil was decreasing at 69300 barrels, yearly</em>

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2 years ago