Problem 3 answer key
Steve’s Big Dig
Grade 3 · Geometry · Number and operations · Data and probability
MJ 5.3 · C2 · W2
Standard challenge · Moderate workload
About 5–14 minutes
Steve’s Big Dig — answer
Problem ID: 3
Part 1 — 1 jewel
Each layer contains 5 × 5 = 25 blocks. There are 5 layers, so:
25 × 5 = 125
Answer: Steve removes 125 blocks.
Part 2 — 2 jewels
One tenth of 125 is:
125 ÷ 10 = 12.5 = 12½
Answer: Steve should expect to find 12½ coal blocks on average.
The expected value is an average across many holes. Steve cannot find half of one block in a single hole, so an actual hole will contain a whole-number amount of coal and may have more or less than the average.