Question

Lucy estimated that is would take 4000 grains of sand to make a pound. That would mean each grain of sand weighs 1/4000 of a pound. In a decimal form, each grain of sand would weigth 0.00025 pounds. Which number expressed in scienfic notation represent the weigth of a grain of sand?

Answer 1

25x10^-5

Explanation:

We are expected to represent the decimal number in scientific notation

the decimal number is 0.00025

Given that the number in decimal is 0.00025 pounds

in scientific notation we will have to count 4 decimal point to the left from the second number which is 2

=2.5x10^-4

or we can still write it as

25x10^-5

either of the above is correct, only take note of the number of places you count and the sign