Question

One of the homework questions. I got the answer 2.48898 x 10 -3 from my calculator. Would I put 2.49 x 10 -3 as my answer...is this correct?

If a 120-lb woman uses five 2.0-lb lead weights in order to submerge during a recent scuba dive, what volume (in cubic centimeters) do the weights occupy if lead has a density of 11.3 g/cc

Answer 1

401.4cm^3

Step-by-step explanation:

1) Rounding depends on how many decimals you want to round to. If, for example, you want to round to two decimals, you would look at the next one, the third; if it is over 5 then you raise second decimal bu one;

3.467 -> 3.47

85.362 -> 85.36

If you want to round to one decimal, you would look at the second:

7.23 -> 7.2

2.59 -> 2.6

So, basically, depending on how many decimals you want to round to, you always look at the next one; if it's 5 or above you raise by one, if not, the last decimal stays.

In this case you are correct, you can round it to 2.49 or 2.5 or 2.489 depending on how many decimals you need.

2) Volume is expressed through an equation:

V = m / ρ

where m is mass and ρ is density.

Here, we are given mass in lb so we first need to convert it to grams.

A pound is equal to 453.59 grams, so two pounds are 2 • 453.59 = 907.18 g

Density is given to be 11.3 g/cm^3.

So, the volume is:

V = 907.18 / 11.3 = 80.28 cm^3.

However, this is the volume of one weight, it is given that she uses five of them.

So the volume of 5 weights will be:

5 • 80.28 = 401.4 cm^3.