Perry has some pink and red marbles. The total mass of all his marbles is 250 g. He has 5 less pink marbles than red marbles. The average mass of the pink marbles is 4 g. The average mass of the red marbles is 6 g. How many marbles does Perry have altogether?
| |
Pink |
Red |
Total |
| Number |
1 u |
1 u + 5 |
2 u + 5 |
| Value |
4 |
6 |
|
| Total value |
4 u |
6 u + 30 |
250 |
Total mass of pink marbles
= 1 u x 4
= 4 u
Total mass of red marbles
= 6(1 u + 5)
= 6 u + 30
Total mass of the marbles
= 4 u + 6 u + 30
= 10 u + 30
10 u + 30 = 250
10 u = 250 - 30
10 u = 220
1 u = 220 ÷ 10 = 22
Total number of marbles
= 2 u + 5
= 2 x 22 + 5
= 44 + 5
= 30
Answer(s): 30
