Answer:
4.6005 * 10^6 grams
Explanation:
Average mass of sand grain = 1.5 * 10^-5 grams
Number of grains in Erin's sandbox = 3.067 * 10^11 grains
To obtain the mass of sand in Erin's grain box :
We multiply the mass per sand grain and the number of grains
(1.5 * 10^-5) * (3.067 * 10^11)
1.5 * 3.067 = 4.6005 * (10^(-5+11))
4.6005 * 10^6 grams