One grain of this sand approximately weighs [tex]\( 7 \times 10^{-5} \)[/tex] g.

b) How many grains of sand are there in 6300 kg of sand? Give your answer in standard form.



Answer :

Let's go through the steps to determine how many grains of sand there are in 6300 kilograms of sand.

1. Convert the total weight from kilograms to grams:

We start by converting the total weight of sand from kilograms to grams. We know that:
[tex]\[ 1 \text{ kilogram (kg)} = 1000 \text{ grams (g)} \][/tex]
So,
[tex]\[ 6300 \text{ kg} \times 1000 = 6300000 \text{ g} \][/tex]
Therefore, 6300 kg of sand is equivalent to 6300000 grams of sand.

2. Determine the weight of a single grain of sand:

According to the provided information, the weight of one grain of sand is:
[tex]\[ 7 \times 10^{-5} \text{ grams} \][/tex]

3. Calculate the number of grains:

To find the number of grains in 6300000 grams of sand, we need to divide the total weight by the weight of one grain of sand:
[tex]\[ \frac{6300000 \text{ g}}{7 \times 10^{-5} \text{ g/grain}} \][/tex]

4. Perform the division:
[tex]\[ \frac{6300000}{7 \times 10^{-5}} \][/tex]
Dividing 6300000 by [tex]\(7 \times 10^{-5}\)[/tex] gives us:
[tex]\[ 6300000 \times \frac{1}{7 \times 10^{-5}} = 6300000 \times \frac{1}{7} \times 10^5 \][/tex]

5. Simplify the expression:
[tex]\[ 6300000 \div 7 = 900000 \][/tex]
Continuing our calculation:
[tex]\[ 900000 \times 10^5 = 9 \times 10^5 \times 10^5 = 9 \times 10^{10} \][/tex]

Therefore, the number of grains of sand in 6300 kilograms of sand is approximately [tex]\(9 \times 10^{10}\)[/tex].

This matches with the numerical answer from the provided result, which is about [tex]\(8.999999999 \times 10^{10}\)[/tex]. For the sake of clarity and standard form, we round this to:

[tex]\[ 9 \times 10^{10} \text{ grains} \][/tex]