Exponents and Scientific Notation

Bob · 2011-07-07 05:09:49

OK

My ruler is 1 foot = 12 inches = about 30 cm.

4.5 Liters is about 1 gallon

1 Kilogram is about 2.2 lb.

5 miles is almost exactly 8 kilometers.

See http://en.wikipedia.org/wiki/Imperial_units

if you want more.

Bob

Bob · 2011-07-07 05:18:18

Incorrect answers:

1-c

I'll post this and continue with the others. Refresh the page to see more.

14-e

That is certainly an identified error. I'm guessing that it is not the first. I would have got this wrong too. Is it something to do with how you place the conversion factors top and bottom in order to identify times and divide? I cannot help more unless I see the 'rules' of this way of doing conversions.

17-d

Same problem here. Your conversion was correct and so you identified an error in the question as required. It's a layout problem again. Sorry.

19-f

This is a GOOD ANSWER. I've got a 0.5L orange carton in my cupboard! The person who set this needs to go shopping!

20-f

And again here. I don't see how we are supposed to know what size can the questioner had in mind!

Don't feel bad about those 5 questions. In 4 out of 5 your mathematics was good.

Bob

Last edited by Bob (2011-07-07 05:29:00)

zee-f · 2011-07-07 05:18:47

i dont get how c for number one was incorrect

(x^3)^5
Ax^-15
Bx^2
Cx^8
Dx^15
Ex^-2
Fx^-8

Bob · 2011-07-07 05:23:36

i dont get how c for number one was incorrect

When you raise to a power (3) and then raise that to another power (5) the 'x' is repeated 15 times not 8. Look back to my earlier post on this.

So 3 x 5 to get 15

not 3 + 5 to get 8

Post #102 has my explanations.

Bob

Last edited by Bob (2011-07-07 05:24:05)

zee-f · 2011-07-07 05:27:56

yup i just saw that sorry 14-e and 17 19 20 are all incorrect

Bob · 2011-07-07 05:30:44

I've edited # 102 to show my view on all of those.

I think you are a victim of poor questions. Let's hope the next set are more reasonable.

With the extra knowledge that the answers we worked out yesterday were not right, I've had a look back at the conversion tables and tried to work out what was expected.

The picture below is my revised attempt at these. I've corrected all errors to show the correct conversions. Cannot guarantee it is what they wanted though. But I feel happier for having tried.

Bob

Last edited by Bob (2011-07-07 06:23:49)

zee-f · 2011-07-12 06:38:34

yeah my algebra lessons are really hard i give up sometimezzz thanx for clearing these out

ps. are 14-e and 17 19 20 are all incorrect?

bobbym · 2011-07-12 08:09:58

Hi zee-f;

Could you please recopy the questions you are having a problem with? This, way people can see them.

zee-f · 2011-07-12 09:07:01

yup sure
19. Estimate the amount of juice in a typical orange juice carton in liters.
Aabout 8 liters
Babout 5 liters
Cabout 4 liters
Dabout 3.5 liters
Eabout 2 liters
Fabout .5 liters

20. Estimate the weight of a small can of soup in grams.
Aabout 30 grams
Babout 500 grams
Cabout 250 grams
Dabout 325 grams
Eabout 750 grams
Fabout 100 grams

zee-f · 2011-07-12 09:08:35

and i need help to explain my new answer for 17 and 14 like am confused i need an explanation

bobbym · 2011-07-12 09:39:52

Let's start with 14 first, which makes sense. Please recopy your work right here.

zee-f · 2011-07-12 09:50:55

ok so for 14 3.25 k =3250000 so my mistake is in the second caulm why???

bobbym · 2011-07-12 09:56:21

Every gram is made up of 1000 milligrams.

3.25 kilograms is equal to 3250 grams. Each of them is made up of 1000 milligrams, so there are

3250 * 1000 = 3 250 000 milligrams

zee-f · 2011-07-12 09:57:33

yup i get that point but like in the picture why is the mistake in the second calum ?

bobbym · 2011-07-12 09:58:17

That is the problem I do not know where the picture is. It is lost in a zillion posts.

zee-f · 2011-07-12 10:01:44

oooh ok hhhhh ill post it right now

bobbym · 2011-07-12 10:03:19

Okay, remember time is money.

zee-f · 2011-07-12 10:04:41

heres the pic

bobbym · 2011-07-12 10:06:53

That was quick, very good. What is wrong with column two?

zee-f · 2011-07-12 10:08:34

there spouse to multiply it by 1000? i dont know thats what am reaalllllly confused at

bobbym · 2011-07-12 10:11:42

The chart says 1 kilogram = 1000 grams. (kilo means 1000).

So to get the number of grams from 3.25 kilograms you would multiply 3.25 kilograms x 1000 = 3250 grams

zee-f · 2011-07-12 10:22:47

ok so what they did incorrect is multiplied or put 1 kg in the second column and there spouse to put 1000 like multiply it by a 1000 right ?

bobbym · 2011-07-12 10:29:19

Yes, the calculation is

3.25 x 1000 x 1000 = 3.25 x 1000000 = 3 250 000

Where did she go?

Bob · 2011-07-12 19:48:09

hi bobbym,

I think the instructions specify a certain layout for doing the conversion. See my diagram in post #104.

I'm guessing that: when the conversion requires a 'multiply' , the factor is put on the top line, and when the conversion requires a 'divide' the factor is put on the bottom.

So the first error occurs because the conversion is shown up-side-down, leading to a second error where the original measurement is divided by 1000 when it should be multiplied.

zee-f correctly did the conversion, so only got the wrong multi-choice answer because of the layout requirement. Maybe she was given instruction on this. In which case it would help to see it.

Bob

bobbym · 2011-07-12 19:52:06

Hi Bob;

I see that she had it explained to her already. I think that she is a little shaken over it. Maybe she got it, I do not know.

Math Is Fun Forum

#101 2011-07-07 05:09:49

Re: Exponents and Scientific Notation

#102 2011-07-07 05:18:18

Re: Exponents and Scientific Notation

#103 2011-07-07 05:18:47

Re: Exponents and Scientific Notation

#104 2011-07-07 05:23:36

Re: Exponents and Scientific Notation

#105 2011-07-07 05:27:56

Re: Exponents and Scientific Notation

#106 2011-07-07 05:30:44

Re: Exponents and Scientific Notation

#107 2011-07-12 06:38:34

Re: Exponents and Scientific Notation

#108 2011-07-12 08:09:58

Re: Exponents and Scientific Notation

#109 2011-07-12 09:07:01

Re: Exponents and Scientific Notation

#110 2011-07-12 09:08:35

Re: Exponents and Scientific Notation

#111 2011-07-12 09:39:52

Re: Exponents and Scientific Notation

#112 2011-07-12 09:50:55

Re: Exponents and Scientific Notation

#113 2011-07-12 09:56:21

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#114 2011-07-12 09:57:33

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#115 2011-07-12 09:58:17

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#116 2011-07-12 10:01:44

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#117 2011-07-12 10:03:19

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#118 2011-07-12 10:04:41

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#119 2011-07-12 10:06:53

Re: Exponents and Scientific Notation

#120 2011-07-12 10:08:34

Re: Exponents and Scientific Notation

#121 2011-07-12 10:11:42

Re: Exponents and Scientific Notation

#122 2011-07-12 10:22:47

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#123 2011-07-12 10:29:19

Re: Exponents and Scientific Notation

#124 2011-07-12 19:48:09

Re: Exponents and Scientific Notation

#125 2011-07-12 19:52:06

Re: Exponents and Scientific Notation

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