Julian has some green and pink marbles. The total mass of all his marbles is 189 g. He has 9 more pink marbles than green marbles. The average mass of the green marbles is 7 g. The average mass of the pink marbles is 11 g. How many marbles does Julian have altogether?
| |
Green |
Pink |
Total |
| Number |
1 u |
1 u + 9 |
2 u + 9 |
| Value |
7 |
11 |
|
| Total value |
7 u |
11 u + 99 |
189 |
Total mass of green marbles
= 1 u x 7
= 7 u
Total mass of pink marbles
= 11(1 u + 9)
= 11 u + 99
Total mass of the marbles
= 7 u + 11 u + 99
= 18 u + 99
18 u + 99 = 189
18 u = 189 - 99
18 u = 90
1 u = 90 ÷ 18 = 5
Total number of marbles
= 2 u + 9
= 2 x 5 + 9
= 10 + 9
= 99
Answer(s): 99
