Assistance required for following

[faisal]

assistance required for following please

3 questions that have driven me up the wall

Homework Statement

0.5km2 is the same area as
a)5x10*6m2
b)5x10*12mm2
c)5x10*9cm2
d)5x10*13mm2

Homework Equations

10*6m=1km2

The Attempt at a Solution

0.5x10*6= 500,000 the answer is a) i don't understand what iv done wrong

q2

Homework Statement

0.04m3 is the same volume as
a)4x10*6mm3
b)40dm3
c)4x105cm3
d)4x10*2dm3

Homework Equations

in 1m3=10*9mm
1x10*9x0.04=4x10*7??

The Attempt at a Solution

the answer is a)

Homework Statement

5x10*8mm2 is the same as
a)500cm2
b)5x10-4km2
c)5m2
d)5x10-2m2
my workings
10*6mm=1m2
1/10*6=1x10-6
1x10-6x5x10*8=5x10*2
the answer is d my answer doesn't come as -2 as it should

 

[faisal]

common guyz I'm dying

 

[drpizza]

Your solution is correct, if there was a choice for meters squared.

You'll need to convert that to mm^s, or cm^2 in order to determine which choice is correct. Working within scientific notation makes it easier, i.e rather than .5 km^2, you could write it as .5 * (10^3 m) ^2
When you square a number with an exponent, you multiply the exponents. Thus, 10^3 squared is 10^6. Thus that equals .5 * 10^6 or in proper scientific notation, 5 * 10^5


the prefix "kilo" can be replaced with 10^3
the prefix "centi" can be replaced with 10^-2
and the prefix "milli" can be replaced with 10^-3

It might be quicker to just convert everything (the choices) to regular SI units.

Thus, something like 15 cubic millimeters would look like this
15 * (10^-3 meters)^3 = 15* 10^-9m^3 or 1.5*10^-8m^3

 

[faisal]

Your solution is correct, if there was a choice for meters squared.

You'll need to convert that to mm^s, or cm^2 in order to determine which choice is correct. Working within scientific notation makes it easier, i.e rather than .5 km^2, you could write it as .5 * (10^3 m) ^2
When you square a number with an exponent, you multiply the exponents. Thus, 10^3 squared is 10^6. Thus that equals .5 * 10^6 or in proper scientific notation, 5 * 10^5


the prefix "kilo" can be replaced with 10^3
the prefix "centi" can be replaced with 10^-2
and the prefix "milli" can be replaced with 10^-3

It might be quicker to just convert everything (the choices) to regular SI units.

Thus, something like 15 cubic millimeters would look like this
15 * (10^-3 meters)^3 = 15* 10^-9m^3 or 1.5*10^-8m^3

if my methods are correcct why are all my answers wrong?

 

[Gokul43201]

0.5*10^6 is not 5*10^6

when you say "the answer is x" are you talking about the choice you believe is the correct answer or are you talking about the answer given by the book. If the latter, they are all wrong. Perhaps you are looking at the wrong part of the answer list?