SME
Grade 6 Science · Problem type
How long a layer took to form
Use this for “About 1 cm of ooze builds up in 1,000 years. How long for 30 cm?”
Diagram
Time in thousands of years: 30 on the top line sits over 30 cm on the bottom line: each 1 above is 1 below.
This is an example. Type your own values to start a new problem.
Layer thickness
example · cm
Rate in cm each 1,000 years
example
Time in thousands of years
calculated
Formulas
30 ÷ 1 = 30
Layer thickness ÷ rate = time in thousands of years
Assumptions
•
The rate is how thick a layer grows in 1,000 years.
•
The deep sea floor gains about 1 cm of shell ooze in 1,000 years; one river flood can leave several centimeters.
•
Layers squeeze thinner as they harden into rock, so the answer is an estimate.
Step-by-step
WE KNOW
Layer thickness: 30 cm
Rate in cm each 1,000 years: 1
FIND
time in thousands of years
Step 1 · Find time in thousands of years
30 ÷ 1 = ?
Layer thickness ÷ rate = time in thousands of years
Each 1,000 years adds one rate’s worth, so divide the thickness by the rate.
Time in thousands of years = 30 (30,000 years)
Check
Put the numbers back in. Both sides should match.
1 × 30 = 30 ✓
Topic check
See what you know: 5 questions on this topic
New questions each time. Pass to mark it complete.