- Estimation is the process of arriving at an approximate answer to a question.
- We use a special math symbol ≈, which mens is approximately equal to
- This can involve rounding numbers to make it easier to perform math
- Example 1: How much would it cost me to buy lunch for the class?
There are 40 people registered
Lunch at Burger King is about $5.00 per meal
So the total will be about $200, nope not gonna happen
- Example 2: My family goes out for lunch, we order dinners that cost $4.92, $6.33, $2.83 and $4.03, plus four drinks at $1.34 each. Estimate the total bill
4.92 ---> 5.00
6.33 ---> 6.00
2.83 ---> 3.00
4.03 ---> 4.00
4 x 1.34 ---> 5.00
----- -----
23.47 23.00
- Note in each case I just changed the numbers to make the math easy.
- Depending on what I am doing, I might want to round the values
3.25 -> 3
3.49 -> 3
3.50 -> 3
3.51 -> 4
3.75 -> 4
- Or I may want to always estimate high, for bills or such
Kirk:
"How long to re-fit?"
Scotty:
"Eight weeks. But you don't have eight weeks, so I'll do it for you in two."
Kirk:
"Do you always multiply your repair estimates by a factor of four?"
Scotty:
"How else to maintain my reputation as a miracle worker?"
From: Star Trek III: The Search For Spock
- The more digits I use when I round, the more accurate the final answer will be, but the more work the math will be.
- Example 3: Estimate the distance from Edinboro to Niagara Falls.
Here is a map
Map quest says the distance is actually 134 miles.
- Example 4: How long will it take to get there?
Most of the way is highway so:
140 miles 1 hour
x ------- ≈ 3 hours
60 miles
- Example 5: How much will it cost to get there?
My car gets 18.453 miles per gallon.
Gas is $2.55 per gallon
140 miles 1 gallon $3.00
x --------- x ------ ≈ $21
20 miles 1 gallon
- Example 6: How many people are in this band?
