Math help from you educators

[USNRET]

I'm stumped, I need an 8th grade math teacher to weigh in.
Edited please see correct home work problem below.

Edited August 29, 2014 by USNRET

[oldtimer]

 I get 1.13% but your rounding may vary.

[oldtimer]

The problem is worded incorrectly though when it says the growth rate is 292000000 as of 2002.  Which is it? The rate or the total?

[oldtimer]

It would not be 292mil plus 3.3.  the rate would be 3.3 divided by 292mil.

[oldtimer]

Of course that is for the first year only.  If the question is from then until now, with a steady growth of 3.3mil per year the calculation is different.

[USNRET]

Calculate the growth rate for the U.S. (show work) -as of 2002, the growth rate for the US population was 292,000,000. The increase in the US population is approximately 3,300,000 a year, from new births and immigration. -Growth rate = amount of change in population /total population x 100 Jeffrey and I disagree. My formula is GR= [3,300,000 / (292,000,000 +3.300,000)] * 100 (3,3000,000 / 295,300,000) * 100 GR=1.12% Anyone?

 

The problem is worded incorrectly though when it says the growth rate is 292000000 as of 2002.  Which is it? The rate or the total?

 

You are right it is stated as this on the home work:

Calculate the growth rate for the U.S. (show work)

-as of 2002, the US population was 292,000,000. The increase in the US population is approximately 3,300,000 a year, from new births and immigration.

-Growth rate = amount of change in population /total population x 100

Jeffrey and I disagree. My formula is

GR= [3,300,000 / (292,000,000 +3,300,000)] * 100

(3,3000,000 / 295,300,000) * 100

GR=1.12%

Is this the correct formula? Anyone?

 

The next question on his home work makes absolutely no sense to me.:

Verbatim

Calculate the doubling rate for the population of the U.S. (show your work)

-The determine doubling time, divide 70 by the population growth rate (hint: see answer to #3 for growrth rate). Yes I checked my typing.

 

It appears to me that copy and paste from the internet for teachers lacks a little proof reading. Jeffrey is an 8th grader in AP classes. Above is from his AP Science class for high school credit.

Edited August 29, 2014 by USNRET

[oscarsear]

Not only is the problem poorly worded but such poorly worded problems get kids into bad habits.  Is there a textbook that goes with this mess, if so, does it provide any insights?  The 'annual' growth rate should be determined by the base population at the start of the year as the prime factor.  If there are 3.3 million (net) new souls then the annual growth rate value can be derived a number of ways and it would be 1.2% (millions of new citizens per year).  Haven't a clue how using that as a factor into the given number of 70 (70 what?) comes up with a 'determine(d) doubling time'.  Using the value (whatever it is) gives a population doubling time of 58.3 (years?).

[tigerwoodKhorns]

 

Calculate the growth rate for the U.S. (show work) -as of 2002, the growth rate for the US population was 292,000,000. The increase in the US population is approximately 3,300,000 a year, from new births and immigration. -Growth rate = amount of change in population /total population x 100 Jeffrey and I disagree. My formula is GR= [3,300,000 / (292,000,000 +3.300,000)] * 100 (3,3000,000 / 295,300,000) * 100 GR=1.12% Anyone?

 

The problem is worded incorrectly though when it says the growth rate is 292000000 as of 2002.  Which is it? The rate or the total?

 

You are right it is stated as this on the home work:

Calculate the growth rate for the U.S. (show work)

-as of 2002, the US population was 292,000,000. The increase in the US population is approximately 3,300,000 a year, from new births and immigration.

-Growth rate = amount of change in population /total population x 100

Jeffrey and I disagree. My formula is

GR= [3,300,000 / (292,000,000 +3,300,000)] * 100

(3,3000,000 / 295,300,000) * 100

GR=1.12%

Is this the correct formula? Anyone?

 

The next question on his home work makes absolutely no sense to me.:

Verbatim

Calculate the doubling rate for the population of the U.S. (show your work)

-The determine doubling time, divide 70 by the population growth rate (hint: see answer to #3 for growrth rate). Yes I checked my typing.

 

It appears to me that copy and paste from the internet for teachers lacks a little proof reading. Jeffrey is an 8th grader in AP classes. Above is from his AP Science class for high school credit.

 

 

I got the same - 1.13% for growth rate and 61.9 years for doubling time. 

 

 

Math problems are very poorly written.  When growing up I thought that math and science were the important subjects and english was too "flowery"

 

I now realize just how important communicating clearly is.  You can be brilliant, but if you cannot communicate clearly and concisely, what good is it? 

[tigerwoodKhorns]

Not only is the problem poorly worded but such poorly worded problems get kids into bad habits.  Is there a textbook that goes with this mess, if so, does it provide any insights?  The 'annual' growth rate should be determined by the base population at the start of the year as the prime factor.  If there are 3.3 million (net) new souls then the annual growth rate value can be derived a number of ways and it would be 1.2% (millions of new citizens per year).  Haven't a clue how using that as a factor into the given number of 70 (70 what?) comes up with a 'determine(d) doubling time'.  Using the value (whatever it is) gives a population doubling time of 58.3 (years?).

 

If the problems were worded correctly the assignment makes sense.  These are very easy equations.  The test is to see if you can convert a simple word problem into an equation. 

 

Many people cannot do this:

 

[USNRET]

AS copied from a conversation I am having with my sister:

 

as stated the change in population is
3,300,000 and that is divided by total population which is (now) 295,300,000 which equals 0.0111

-Growth rate = amount of change in population /total population x 100

0.0111*100 = 1.1175%

 

I don't have a clue how the doubling is calculated

[USNRET]

I now see present - past / past or (295,300,000 - 292,000,000) / 292,000,000 = 1.13%

[BigStewMan]

i guess you have to cut the number if half if you’re traveling more than a mile a minute…that’s why i flunked math --now it makes sense.

[USNRET]

Now to doubling population
I increase population by 1.13% per year

how long until I double population?

is 1.13x = 100 correct?

100/1.13 = 88.495 years

[USNRET]

I got the same - 1.13% for growth rate and 61.9 years for doubling time.

Please show formula for doubling

[USNRET]

I have found 70/1.13 = 61.9 or 62 years

Glad I am not in school!

[Quiet_Hollow]

Just the tip of the iceberg. Wait until college...it get's much, much worse. Especially in the technical fields where the focus is primarily on the correct solution at almost the complete expense of everything else.

 

I now realize just how important communicating clearly is.  You can be brilliant, but if you cannot communicate clearly and concisely, what good is it? 

Amen! 

[tigerwoodKhorns]

Now to doubling population

I increase population by 1.13% per year

how long until I double population?

is 1.13x = 100 correct?

100/1.13 = 88.495 years

 

Forgot about compounding. 

 

Base number x (1+i)^n is the formula if I remmeber correctly. 

 

So 1.013^62 = 2.22 or roughly doubling.

 

So the lower number from the 70 divided by increase seems reasonable. 

[tigerwoodKhorns]

 

Just the tip of the iceberg. Wait until college...it get's much, much worse. Especially in the technical fields where the focus is primarily on the correct solution at almost the complete expense of everything else.

 

 

 

 

I was an engineer and I am now an attorney.  Communication in both fields is a mess. 

 

I use a technical style of writing which is not common for attorneys.  Lots of headings, short lists (as much as possible) and short phrases.  I also try to keep documents very organized.  If we have terms that relate to due diligence, they ALL go in one section, not scattered throughout a 40 page document.  You have to see the messes that I am given to review.