Question

Richard records the weight of his two pets in a table, as shown. After how many weeks were the pets the same weight? What was their weight at that time? Pet 1 Week Weight (grams) 0 400 2 800 Pet 2 Week Weight (grams) 0 500 2 700 At 1 week, they both weighed 600 grams. At 2 weeks, they both weighed 500 grams. At 3 weeks, they both weighed 650 grams. At 4 weeks, they both weighed 1,000 grams.

Answer 1

Pet 1 Pet 2
0 - 400 0 - 500
1 - 600 1 - 600
2 - 800 2 - 700
3 - 1000 3 - 800

Option A - At 1 week, they both weighed 600 grams.

Answer 2

After week 1 both the pets were having same weights of 600 gms.

Explanation:

As given in the question weights of two pets are

Week weight of pet 1(in gm) weight of pet 2(in gm)

0 400 500

1 600 600

2 800 700

3 1000 700

In this table weights of the pets at 0 wk and 2 wk has been given only and we have calculated the weights by averaging their weights at 1 and 3 wk.

1). weight at 1 week = (weight at 0 wk + weight at 2 wk)/2

weight of pet 1 = (400+800)/2 = 600 gm

weight of pet 2 = (500 + 700)/2 = 600 gm

2).weight at 2 week = (weight at 1 wk + weight at 3 wk)/2

Therefore weight after 3 week = 2×weight after 2 week - weight after 1 week.

weight of pet 1 = 2×800 - 600 = 1600-600 =1000 gm

weight of pet 2 = 2×700 - 700 = 700 gm.

Now we have got the answer from the table formed that after 1 week both the pets were of same weight 600 gm.