Ian has some brown and pink marbles. The total mass of all his marbles is 197 g. He has 9 less brown marbles than pink marbles. The average mass of the brown marbles is 5 g. The average mass of the pink marbles is 6 g. How many marbles does Ian have altogether?
| |
Brown |
Pink |
Total |
| Number |
1 u |
1 u + 9 |
2 u + 9 |
| Value |
5 |
6 |
|
| Total value |
5 u |
6 u + 54 |
197 |
Total mass of brown marbles
= 1 u x 5
= 5 u
Total mass of pink marbles
= 6(1 u + 9)
= 6 u + 54
Total mass of the marbles
= 5 u + 6 u + 54
= 11 u + 54
11 u + 54 = 197
11 u = 197 - 54
11 u = 143
1 u = 143 ÷ 11 = 13
Total number of marbles
= 2 u + 9
= 2 x 13 + 9
= 26 + 9
= 54
Answer(s): 54
