Julian has some brown and blue marbles. The total mass of all his marbles is 211 g. He has 7 more blue marbles than brown marbles. The average mass of the brown marbles is 3 g. The average mass of the blue marbles is 5 g. How many marbles does Julian have altogether?
| |
Brown |
Blue |
Total |
| Number |
1 u |
1 u + 7 |
2 u + 7 |
| Value |
3 |
5 |
|
| Total value |
3 u |
5 u + 35 |
211 |
Total mass of brown marbles
= 1 u x 3
= 3 u
Total mass of blue marbles
= 5(1 u + 7)
= 5 u + 35
Total mass of the marbles
= 3 u + 5 u + 35
= 8 u + 35
8 u + 35 = 211
8 u = 211 - 35
8 u = 176
1 u = 176 ÷ 8 = 22
Total number of marbles
= 2 u + 7
= 2 x 22 + 7
= 44 + 7
= 35
Answer(s): 35
