Question

You and your friend each collect rocks and fossils. Your friend collects three times as many rocks and half as many fossils as you. You collect 20 objects. Your friend collects 20 objects. How many rocks and how many fossils do you each collect?

Answer 1

Answer:

I collect 4 rocks and 16 fossils. While my friend collects 12 rocks and 8 fossils.

Step-by-step explanation:

The number of total objects collected by me  = 20

The number of objects collected by my friend  = 20

Let us assume:

The number of rocks collected by me  = m

The number of fossils collected by me  = 2 k

⇒ m +  2 k =  20  .... (1)

So, according to the question:

The number of rocks collected by my friend = 3 x (rocks collected by me)  

= 3 x (m)  = 3 m

The number of fossils collected by my friend = 1/2 x (fossils collected by me)    = 1/2 x (2k )  = k

⇒ 3 m +   k =  20  .... (2)

Solving (1)and (2) for the value of m and k, we get:

m +  2 k =  20     ⇒ m = 20 - 2 k ... Put this in (2)

3 m +   k =  20  ⇒  3 (20 - 2 k) +  k = 20

⇒ 60 - 6 k +  k  = 20

or, - 5k = -40

or, k = 40/5  = 8

⇒ k= 8

m + 2(8)  = 20

or, m = 4

Hence, the number of rocks collected by me  = m = 4

The number of fossils collected by me  =  2 k = 2 (4)  = 16

Hence, the number of rocks collected by my friend   = 3 m  = 3 x 4 = 12

The number of fossils collected by my friend   =   k =  8

Hence, I collect 4 rocks and 16 fossils. While my friend collects 12 rocks and 8 fossils.