Question

If the cost of 1 liter of cough syrup is Rs. 480.40, find the cost of 500ml.
(a) Rs. 200.40
(b) Rs. 220.40
(c) Rs. 260.40
(d) Rs. 240.20

Answer 1

Hint: To solve the question given above, we will first find out the cost of 1ml of cough syrup in rupees with the help of conversion, 1 liter = 1000ml. With the help of this, we will find the cost of 1ml of cough syrup. After that, to find the cost of 500ml of cough syrup, we will find the cost of 1ml of cough syrup with 500.

Complete step-by-step answer:
It is given in the question that the cost of 1 liter of cough syrup is Rs. 480.40 and the cost which we have to find is 500ml. Thus, we can see that there are two different units of measurement. So, we will have to find the relation between these two units – liters and ml. The relation between liter and ml is shown as 1 liter = 1000 ml.
Now, we will find the cost of 1ml of cough syrup. The cost of 1ml of cough syrup is obtained as,
Cost of 1 liter cough syrup = Rs. 480.40.
We can also say that, the cost of 1000ml of cough syrup = Rs. 480.40.
So, the cost of 1ml of cough syrup will be \[\dfrac{Rs.480.40}{1000}=Rs.0.48040.\]
Now, we will find the cost of 500ml of cough syrup. It will be obtained by multiplying the cost of 1ml of cough syrup by 500. Thus, we will get,
Cost of 500ml cough syrup = 500 \[\times \] (Cost of 1ml of cough syrup)
Cost of 500ml cough syrup = 500 \[\times \] Rs. 0.48040
Cost of 500ml cough syrup = Rs. 240.20
Hence, option (d) is the right answer

Note: We can also solve the above question alternatively by the following method. It is given that the cost of 1 liter cough syrup is Rs. 480.40 and we have to find out the cost of 500ml cough syrup. The cost is proportional to the quantity of cough syrup. Thus, we have,
\[Rs.480.40=1\times k....\left( i \right)\]
where k is a constant. We know that, \[500ml=\dfrac{1}{2}liter.\]
Let the cost be Rs. x. Thus, we have,
\[Rs.x=\dfrac{1}{2}\times k......\left( ii \right)\]
Dividing (i) by (ii), we have,
\[\dfrac{Rs.480.40}{Rs.x}=\dfrac{1\times k}{\dfrac{1}{2}\times k}\]
\[\Rightarrow \dfrac{Rs.480.40}{Rs.x}=2\]
\[\Rightarrow x=\dfrac{Rs.480.40}{2}\]
\[\Rightarrow x=Rs.240.20\]