Question

$1.2$Kg of chocolate costs rupees$974.40$.Find
1) The cost of $1$kg of chocolate
2) The cost of $0.8$kg of chocolate

Answer 1

Hint:
When more than $1$kg of the things cost is given then we need to find cost per kg by dividing the cost of given kg to given kg. From that we can find a cost of less than $1$kg by multiplying the kg to the cost of per kg.

Complete step by step solution:
Here we have $1.2$kg of chocolate which cost rupees $974.40$. From that we need to find the cost of $1$kg of chocolate and the cost of $0.8$kg of chocolate
1) The cost of $1$kg of chocolate.
Here more than $1$kg of cost is given so we need to find $1$kg cost.
To find $1$kg cost we need to divide the given cost by the given kg.
Here the given kg is $1.2$
For that kg the given cost is $974.40$
$\Rightarrow $ Cost per kg = Cost of given kg ÷ given kg
Apply the value to this we get,
$\Rightarrow $ Cost per kg $=\dfrac{974.40}{1.2}$
To take the decimal out we can multiply both by $100$ because we have two numbers after the decimal points, then we have
$\Rightarrow $ Cost per kg $=\dfrac{974.40}{1.2}\times \dfrac{100}{100}$
$\Rightarrow $ Cost per kg $=\dfrac{97440}{120}$
By cancelling we get
$\Rightarrow $ Cost per kg $=812$
The cost of $1$kg of chocolate is $812$
2) The cost of $0.8$kg of chocolate.
Here we need to find less than $1$kg. We already know the cost of $1$kg so multiply $0.8$ to the cost of $1$kg.
$\Rightarrow $ Cost of $0.8$kg = Cost of $1$kg $\times 0.8$
Apply the value we get,
$\Rightarrow $ Cost of$0.8$kg = $812\times 0.8$
Multiply these numbers we get,
$\Rightarrow $ Cost of $0.8$kg = $649.6$
The cost of $0.8$kg is $649.6$

Note:
If the cost of $1$kg is given and we need to find the cost of grams value. In this case we need to convert kg into grams and then we need to find cost per gram by dividing the cost of given grams to given grams.