ESTIMATION PRACTICE · SET L03
The city adds up
Explore how individual rates and capacities become city-scale totals. These exercises ask you to connect a rate or an average with the population, duration or capacity described in the prompt. Use only the stated assumptions, and check that the final unit answers the question rather than an intermediate step.
Three questions · Untimed solo practice · Calculator and scratch notes available
Answers and worked explanations appear after you submit each estimate. Replaying keeps your first completed score.
Questions and ways to approach them
QUESTION 1 · City life
A café sells 240 coffees a day, using 18 g of beans per cup. How many kilograms of beans does it use in 30 days?
Answer in: kilograms
Start with beans used for one day: cups sold multiplied by grams per cup. Extend that amount to thirty days, then convert grams to kilograms. Keep daily consumption separate from the monthly total.
QUESTION 2 · Transport
A bus route runs 40 buses, each making 12 trips a day with an average of 35 passengers. How many passenger trips is that per day?
Answer in: passenger trips
Calculate passenger trips for one bus, then scale to the whole fleet. A passenger who rides twice counts as two trips; the question does not ask for the number of distinct people. Keep average occupancy separate from the number of journeys.
QUESTION 3 · Everyday
A city has one million residents. If each drinks 2 litres of water a day, how many litres do they drink in 365 days?
Answer in: litres
Work out daily drinking water for the city, then extend it to the stated year. This is drinking water only, not total household water use. Keep the population factor and the time factor separate so neither is counted twice.
Review the reasoning, then try again
A close answer is useful, but so is knowing where an estimate went wrong. After each reveal, compare your assumptions with the worked explanation. Look for a unit conversion, a repeated factor or an uncertain starting value before deciding what to change on a replay.
Each round scores the ratio of the larger number to the smaller. A perfect estimate is 1×. Your three-round score is the arithmetic average of those ratios, so a large miss can outweigh two close answers. Read the scoring rules and examples.