1. Answer: 4.5 hour
The equation for time needed to prepare the diner is H/6 + H/18 = 1
To solve this question, you have to equalize the denominator of the equation. The greatest common multiple of 6 and 18 is 18, so you have to change the denominator to 18. The calculation would be:
H/6 + H/18 = 1
H/6 * 3/3 + H/18 = 1
3H/18 + H/18 = 1
4H/18 = 1
H= 18/4= 4.5
2. Answer: 9.2 grams
Halley measured samples of a metallic substance for an experiment on density with equipment that has lowest unit 1/10 gram or 0.1 gram. The equipment should not be able to differentiate unit lower than 0.1 gram, so it is not possible to have result such as 9.24 grams. or 9.244 grams.
3. To find the formula to find length of a rectangle from its perimeter you need to move the length(l) into the left of the equation. The calculation would be:
p = 2L + 2w
p-2w=2L
2L= p-2w
L=1/2p -w
The equation of I is right, but the equation of II and III is not.
I. L= 1/2p - w ----> right
II. L=(p - 2w) ---> wrong, should be 2L=(p - 2w)
III. L= P-2w / 2---> wrong, should be L= (P-2w)/ 2
