In this workout, we're being asked to calculate the weighted average exam score. We're asked to calculate it first, using the intermediate step of weighted values, then calculate it directly from the inputs using some products.

So here we've got three exams, and then we've got exam scores for each of them, and exam weighting. I can see that exam one does not count very much towards the final grade. It's only 10%. Same for exam two, but exam three has a much higher weight of 80%.

Let's find each of the weighted values. So we multiply the score by the exam weighting, and then I can use the fill handle at the bottom, drag that down, and then I can sum it up. And the overall weighted average exam score is 82.5%. Let's see if some products can do that.

So I type in the formula, sumproducts, open brackets, and it asks me for the two arrays. The first one is the exam score, and the second one is the exam waiting. And as I close the brackets, it will multiply those two arrays together, then sum each of the answers, and we get exactly the same answer as before. So sumproduct is that little bit quicker.

Let's look at another workout. This one's asking us to calculate total rental income. Again, it asks us to calculate it first, using the intermediate step of total rent, then calculate it directly.

In this example, we've got some buildings. Strathmore has 20 parking spots, but it's then got a vacancy rate of 30%. This means 30% the time the parking spots are empty. We've got the rent per spot, and we've calculated the occupancy rate as 1 minus the 30%. So for the total rent here, I'm going to need to multiply three items together, the number of parking spots and the rent per spot and the occupancy rates. And that will give me total rent for the Strathmore building of 44.8.

I can copy that down. I'm going to select down and then copy down with control D and then sum them up. So total rental income here, 92.8 from all of those parking spots. But some products can do it a little bit quicker. We're going to need to select three arrays this time, the parking spots, the rent per spot, and the occupancy rates.

It will multiply each of those together similar to the total rent column, then sum them up and we get the same number, 92.8. So sumproducts allows us to avoid that intermediate step.