6 P5.ST.JC.18121202
Level 3
The average cost of some books is $75.
When another 3 books are added,
the total cost increases by $190.
The average cost becomes $70.
How many books are there in the end?
3 m
2 averages Averaging out Average with unknown quantity Number x value Units equations Units table
7 P5.ST.JC.18121203
Level 3
The average cost of some books is $30.
When a book that costs $90 is added,
the average cost of the books becomes $40.
How many books are there in the end?
3 m
2 averages Averaging out Average with unknown quantity Number x value Units equations Units table
8 P5.ST.JC.18121204
Level 3
The average cost of some books is $30.
When a book that costs $90 is removed,
the average cost of the books becomes $10.
How many books are there in the end?
3 m
2 averages Averaging out Average with unknown quantity Number x value Units equations Units table
9 P5.ST.JC.18121205
Level 3
The average cost of some books is $30.
If 3 of the books are now each $15 more,
the average cost of the books becomes $35.
How many books are there altogether?
3 m
2 averages Averaging out Average with unknown quantity Number x value Units equations Units table
10 P5.ST.JC.18121206
Level 3
The average cost of some books is $30.
If 3 of the books are now each $15 more and
2 of the books are now each $5 less,
the average cost of the books becomes $32.
How many books are there altogether?
3 m
2 averages Averaging out Average with unknown quantity Number x value Units equations Units table

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