Paul has some white and yellow marbles. The total mass of all his marbles is 181 g. He has 7 less white marbles than yellow marbles. The average mass of the white marbles is 4 g. The average mass of the yellow marbles is 7 g. How many marbles does Paul have altogether?
| |
White |
Yellow |
Total |
| Number |
1 u |
1 u + 7 |
2 u + 7 |
| Value |
4 |
7 |
|
| Total value |
4 u |
7 u + 49 |
181 |
Total mass of white marbles
= 1 u x 4
= 4 u
Total mass of yellow marbles
= 7(1 u + 7)
= 7 u + 49
Total mass of the marbles
= 4 u + 7 u + 49
= 11 u + 49
11 u + 49 = 181
11 u = 181 - 49
11 u = 132
1 u = 132 ÷ 11 = 12
Total number of marbles
= 2 u + 7
= 2 x 12 + 7
= 24 + 7
= 49
Answer(s): 49
