Lesson 2 of 11
The weighted sum
Show on a big screenAdding shop prices, you keep one running total. It grows with each price you add. The rule's sum works the same way.
Step 1 of 3
- Two inputs: gauge 6, days 1. Sum starts at 0.
- Gauge scaled by weight 6: sum becomes 36.
- Days scaled by weight 4: sum becomes 40.
The rule
Each input is scaled by its own weight. The scaled values add into one sum.
- Input — a number the rule reads — the gauge or the days.
- Weighted sum — every input times its own weight, all added together.
Scaled by its weight means multiplied by it. The starter weights are gauge weight 6 and days weight 4. Now work out another day yourself: gauge 2, days 1. Gauge: 2 × 6 = 12. Days: 1 × 4 = 4. The sum is 12 + 4 = 16. The log is the caretaker's list of 12 days. Every day in it works the same way. One multiply per input, then one add.
The lab below steps one sum, line by line. Predict each running total before you reveal it.
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Try the lab to finish this lesson.