Practice · Grade 7 Percentages
Time Percentage — Practice Problems
Practice problems on the time share of a duration, rising in difficulty: part ÷ total · 100, same unit. A hint and full working for every question, free.
Q1 of 7
0 correct
What share is 90 minutes of 480 minutes? Answer in percent.
90 ÷ 480 · 100
Quick answer
How do I best practise the time percentage?
Work through several problems that rise in difficulty using the same recipe: part ÷ total · 100. The key step is converting both durations to the same unit first (e.g. 8 hours = 480 minutes). Start with clean shares such as 45 of 180 (= 25%), then move to awkward values like 1 of 24 (≈ 4.17%). Check every answer: the ratio times the total should give the part back.
HowTo
A 4-step solving strategy
This order works for any time-share problem — whether the durations are given in minutes, hours or days.
- 1Step 1 of 4
Make the units match
Check the units of part and total first. If they differ (e.g. minutes vs. hours), convert both to the same unit: 8 hours is 480 minutes. This step is the single most common source of error.
- 2Step 2 of 4
Assign part and total correctly
The part goes in the numerator, the total in the denominator. In "90 min of 480 min", 90 is the part and 480 is the whole — so 90 ÷ 480, not the other way round.
- 3Step 3 of 4
Divide, then multiply by 100
Compute part ÷ total and multiply the ratio by 100: 90 ÷ 480 = 0.1875 → 0.1875 · 100 = 18.75%. For awkward values, round sensibly (e.g. to two places).
- 4Step 4 of 4
Check your answer
Multiply the ratio back by the total duration: 0.1875 · 480 = 90 min. If you get the original part, the work is right. If the result is over 100%, you swapped part and total.
Examples
Worked practice examples
Four typical time-share problems. Try each one yourself first, then compare with the working.
Easy
What percent of 480 min is 90 min?
90 ÷ 480 · 100
= 0.1875 · 100
= 18.75%
Check: 0.1875 · 480 = 90 min ✓
Standard case: both values already in minutes, so divide directly.
Easy
What percent of a day is 6 hours?
6 ÷ 24 · 100
= 0.25 · 100
= 25%
Check: 0.25 · 24 = 6 h ✓
A day has 24 hours. 6 hours is a quarter of that.
Medium
What share is 90 min of an 8-hour day?
8 h = 480 min | match the unit
90 ÷ 480 · 100
= 18.75%
Check: 0.1875 · 480 = 90 min ✓
Here the units must be matched first: convert 8 hours to minutes.
Hard
What time share is 200 of 365 days?
200 ÷ 365 · 100
= 0.547945… · 100
≈ 54.79%
Check: 0.547945 · 365 ≈ 200 days ✓
Awkward value — round the result sensibly, here to two decimal places.
Pitfalls
Common mistakes — and how to avoid them
These traps show up again and again with time-share problems.
Dividing different units
Dividing 90 minutes by 8 hours is nonsense. Convert both to the same unit first: 8 hours = 480 minutes, then 90 ÷ 480.
Part and total swapped
The whole (the total duration) always goes in the denominator, the part in the numerator. Swap them and you get a value over 100%.
Forgetting the · 100
90 ÷ 480 = 0.1875 is only the ratio. To get percent you still need · 100, otherwise you report 0.1875% instead of 18.75%.
Not questioning a result over 100%
If the part is not larger than the whole, the result cannot exceed 100%. If it does, recheck the assignment and the units.
Rounding wrong or not at all
Awkward values like 1 ÷ 24 must be rounded. State how many places — and round consistently, not differently each time.
Study
Practise with a plan — three quick tips
Units first, then calculate
Make it a habit to check and match the units before every problem. Automate this and you sidestep the most common mistake from the start.
Memorise common shares
25% = a quarter, 50% = a half, 75% = three quarters. Keeping these reference points in mind tells you at a glance whether a result is plausible.
Always check your answer
Multiply the ratio back by the total duration. If you get the part, the work is right — a check that costs only seconds.
FAQ
Practice FAQ
Glossary
Terms in one sentence
- Time share
- The share of a part duration in a total duration, expressed in percent.
- Part duration
- The shorter span whose share you are looking for — it goes in the numerator.
- Total duration
- The reference time that equals 100% — it goes in the denominator.
- Ratio
- The result of part ÷ total as a decimal, before multiplying by 100.
- Match the unit
- Convert part and total to the same time unit before dividing.
- Utilisation
- An application of the time share: the portion of used time within the available time.
- Check
- Verification by working backwards: ratio · total duration must give the part.