Answer:
66 g
Explanation:
You want the combined mass of pebbles that are 4.5 grams or more, given the histogram of masses.
Histogram
Each dot in the diagram represents one pebble, so the 5 dots above the mass of 4.5 g mean there were 5 pebbles with that mass.
The total mass of pebbles with mass 4.5 g or more will be the sum of the masses of each of the pebbles located in that column, and the columns to its right. Of course, we can use multiplication to simplify the repeated addition:
5×(4.5 g) +4×(5 g) +3×(5.5 g) +1×(7 g) = 66 g
The combined mass of the pebbles 4.5 g or more is 66 g.