Income split (salary and tips): A driver's tips in a week were 5/4 of his salary. What fraction of his total income came from tips?
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A4/9
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B5/9
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C5/8
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D5/4
Answer
Correct Answer: 5/9
Explanation
Introduction / Context:This is a ratio-to-fraction conversion. Given a part (tips) relative to another part (salary), we first express both as parts of the whole, then compute the fraction for tips over total income.Given Data / Assumptions:
- Let salary = S.
- Tips = (5/4)S.
- Total income = S + tips.
Concept / Approach:Compute total = S + (5/4)S. Then tips fraction = tips / total. Simplify by factoring S and cancelling common factors.
Step-by-Step Solution:
Total = S + (5/4)S = (9/4)S.Fraction from tips = [(5/4)S] / [(9/4)S] = 5/9.Verification / Alternative check:Pick a concrete S (e.g., 4). Tips = 5; total = 9; tips/total = 5/9. The fraction is independent of S, confirming the algebra.
Why Other Options Are Wrong:
- 4/9: Would correspond to tips being 4/5 of salary, not 5/4.
- 5/8: Ignores the correct total; 5/8 would mean total of 8 units with tips 5, but here total is 9 units (4 salary + 5 tips).
- 5/4: That is the ratio of tips to salary, not the fraction of total income.
Common Pitfalls:Confusing ratio “of salary” with fraction “of total income.” Always compute the whole first, then form the desired part/whole fraction.
Final Answer:
5/9