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2 years ago

7. Jennifer is 6 years older than Sue. In 4 years, she will be twice as old as Sue was 5 years ago. Find their ages

Mathematics

1 answer:

makvit [3.9K]2 years ago

4 0

Answer: Sue is 20 and Jennifer is 26

Step-by-step explanation:

Let's say that J=Jennifer's age now and S=Sue's age now.

We know that:

J=S+6

Because Jennifer is 6 years older than Sue.

We also know that when Jennifer is 4 years older (J+4), she will be twice as old as Sue was 5 years from now (S-5).

So we get the following equation from that information:

J+4=2(S-5)

So we have the two equations:

J+4=2(S-5)

J=S+6

Let's substitute J=S+6 into the first equation (note that RHS means Right Hand Sie and LHS means Left Hand Side):

(S+6)+4=2(S-5)

S+10=2S-10 [Add 6+4 on the RHS, and distribute on the LHS]

S=2S-20 [Subtract 10 from both sides]

-S=-20 [Subtract 2S from both sides]

S=20 [Divide both sides by -1]

So we know S, which is Sue's age, is 20. So Sue is no 20 years old.

Finding Jennifer's age now is simple. We know Jennifer is 6 years older than Sue, and Sue is 20, so Jennifer is 26 years old.

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Circletown's limits form a perfectly circular shape. It has a population of

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Answer:

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Step-by-step explanation:

Given,

Total population = 20,000 people

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$A = \dfrac{20000}{480}$

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5 0

3 years ago

Read 2 more answers

Help please thank you!

Liula [17]

97 rounds up to 100
78 rounds up to 80
100x80= 8,000
estimate=8,000

97x78=7,566
product=7,566

7 0

2 years ago

Read 2 more answers

An object is heated to 100°. It is left to cool in a room that

stepladder [879]

Answer:

Step-by-step explanation:

Use Newton's Law of Cooling for this one. It involves natural logs and being able to solve equations that require natural logs. The formula is as follows:

$T(t)=T_{1}+(T_{0}-T_{1})e^{kt}$ where

T(t) is the temp at time t

T₁ is the enviornmental temp

T₀ is the initial temp

k is the cooling constant which is different for everything, and

t is the time (here, it's in minutes)

If we are looking first for the temp after 20 minutes, we have to solve for the k value. That's what we will do first, given the info that we have:

T(t) = 80

T₁ = 30

T₀ = 100

t = 5

k = ?

Filling in to solve for k:

$80=30+(100-30)e^{5k}$ which simplifies to

$50=70e^{5k}$ Divide both sides by 70 to get

$\frac{50}{70}=e^{5k}$ and take the natural log of both sides:

$ln(\frac{5}{7})=ln(e^{5k})$

Since you're learning logs, I'm assuming that you know that a natural log and Euler's number, e, "undo" each other (just like taking the square root of something squared). That gives us:

$-.3364722366=5k$