Page 302 - ICSE Math 7

RATIO, PROPORTION AND UNITARY METHOD
Integrated with Science

The concept of ratio and proportion is used by doctors and nurses when administering medication.
Nurses need to know how much medicine a patient needs according to their weight. For example, a
doctor orders 25 mcg per kg per min (1 mcg = 0.001 mg) for a patient having weight 50 kg. In order
to do this, the nurse must convert the mcg (micrograms) to mg (milligrams).

We can convert 25 mcg in mg by setting up a proportion.
1 : 0.001 = 25 : x
⇒ 1 = 25
0.001 x
⇒ x = 0.025
Therefore, if the patient weighs 50 kg, then the dosage received by the patient

= (0.025 × 50) mg per minute
= 1.25 mg per minute or 75 mg per hour
Using the above calculation, calculate how much medicine the nurse should administer to a patient
having weight 56 kg, if doctor orders 30 mcg per kg per min.

PERCENTAGES
Integrated with Geography
5 endangered species on earth and their approximate population are listed in the given table.

Endangered Species Approximate Population
Giant Panda 1,864
Gorilla 100,000
Snow Leopard 6,500

Asian Elephant 45,000
Tiger 3,890

Calculate the following using the above information.
(a) What is the percentage of Giant panda in the total population of the given species?
(b) What is the percentage of Gorilla in the total population of the given species?
(c) What is the percentage of Snow Leopard and Asian Elephant together in the total population of
the given species?

PROFIT AND LOSS
Integrated with Real Life
Rishi has a budget of ` 80,000 for a party. He contacts three management companies to organize the
party. The offers given by the companies are shown in the table.

Company A 10% discount on total budget plus compulsory DJ music worth ` 10,000

Company B 8% discount on total budget and an extra charge of ` 8,000 for DJ music
Company C A flat discount of ` 2,500

Which company’s offer is profitable for Rishi?

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