Old fashioned teacher

Mister Bablu Svenson had been teaching in this village primary school in India for 40 years. He had a unique way of teaching in which he did not allow students to ask any questions. If the students asked any questions, he scolded them and said: Just pay attention to what I say and make notes. Your exam questions will be based on what I say.

This was one of those days. He started reading out from his notes on Indian geography. He was proud that he revised them based on a recent census. Here it went.

Census data

“The population of India is 1,290,000,000. Of these 80.6% are Hindus, 13.4% are Muslims, 2.3% are Christians, 1.9% are Sikhs and 1.9% are others. The sex ratio (males/ females) in India is 107.58. Of the total population 74.04% are literate. The literacy rate is 82.14% in males and 65.46% in females. Kerala has a population of 33,387,677 and it has the highest literacy rate at 93.91%. In Kerala 96% of the males are literate and 92% of the females. Bihar has a population of 103,800,000 but it has the lowest literacy rate at 63.82%. In Bihar 73.39% of the males are literate and only 53.3% of the females. In some small villages the literacy is even lower. For example in the village of Dala in Bihar, the population is 429 of which 226 are males and 203 are females. The literacy rate in this village is 58% among males but among females it is only 31%.

Make sure that you have taken your notes accurately.”

Peter (raised his hand): Sir, I am confused. What is %.

Mr. Svenson became furious

Mr. Bablu Svenson became furious. He gave Peter a stern warning, and told him to refrain from talking in his class from now onwards.

Peter was not the only one who was upset with this teacher. On the way from school to home, Tanya, Tinku and Kate told him that they were also frustrated. Tanya wanted to go complain to the principal but Kate convinced her that they should deal with this issue through their parents. So, Tanya asked them to come over to her place to tell the story to her mom.

Tanya: Mom, something really bad happened at school. Our teacher was teaching about India. Peter asked him a question to explain something, and the teacher just got angry at him.

Tanya ‘s mom: Who is the teacher and what question did Peter ask?

Peter: Mr. Bablu Svenson is the teacher. He was using the word percent. I did not know what it meant, and I asked him.

Tanya ‘s mom: Listen, Mr. Bablu Svenson has been teaching for 40 years. Many of your teachers were not even born when he started teaching. Everyone in school respects his seniority, and he is going to retire in 2 months. So, there is no point in going to the principal.

Peter: What about my question then?

What is a century?

Tanya’s mom: Do you know what a century is?

Peter: Of course, I know. When a batter scores 100 runs, we call it a century.

Tanya: I thought a century could be 100 of anything. It could also means 100 years.

Tanya ‘s mom: Let’s go with 100 runs for now. If a batter has scored 24 runs in homeruns out of 100 runs in total, we will just say that he hit 24 runs per century as homeruns or 24 percent. We can also write it as 24%.

Tinku: What if the batter scores 150 runs total and only 24 runs are as homeruns?

Tanya ‘s mom: We can write this as a fraction: 24/150. Now we can convert this to a fraction where the denominator is 100. That comes to 18/100 or 18%. So percent is just a fraction in which the denominator is 100 or century. It is just a way of converting different fractions into a standard form so that you can compare them.

Percent values allow better comparison

Kate: He said that Kerala has a population of 33,387,677 and it has the highest literacy rate at 93.91%. What does that mean?

Tanya: Look at this way (31,354,367/33,387,677) x 100 is 93.91%. So it means that in Kerala 31,354,367 persons out of a total of 33,387,677 are literate.

Peter: Bihar has a population of 103,800,000 but it has a literacy rate of 63.82%. That means in Bihar 66,245,160 persons out of a total of 103,800,000 are literate.

Kate: Peter, are you saying that there are more literate people in Bihar?

Tanya: He is saying two things. First is that there are a lot more people in Bihar than in Kerala. The second is that whereas most of the Kerala people are literate, in Bihar only 63.82 out of every hundred are literate. About one in three Biharis is not literate.

Tanya’s mom: Now you see how you can make comparisons of fractions using percent. That is the big advantage.

Tanya’s mom: Peter, Tinku and Kate, please call your parents and tell them that you are here. I will get some refreshments ready for all of you. In the meantime make a table to show the data for Dala in your notes as fractions and then convert them into percent.

Practice table

Here is the Table the children made. When they were given the population, they converted it into a fraction and a percent value. When the percent value was given, they convert it into a fraction.

Dala Village	Fraction	Percent
Population, males	226/429	53
Population, females	203/429	47
Literacy, males	131/226	58
Literacy, females	63/203	31

Tanya’s mom was happy with the work the children had done. Tanya was not happy because in the whole village of Dala, there were only 63 literate females. Only 31% were literate and 69% were not. That meant that if you met a female from that village about two women out of three were illiterate. That made her sad.

Next day on the way to school

Tinku: I talked to my dad about the percent thing last night. He told me that every year, my parents put $10,000 into an account for my college education, also that each year the bank pays an interest of 8% on this amount. So, I guess the banks also use the percent thing.

Tanya: Tinku, if you don’t work hard, you might become one of the 20% students who cannot get admission in any college. Here, this is another use of the percent thing.

Peter: You can use percent anywhere like how much percent of the distance to school we have already walked. If a guy buys something for $20 and sells it for 30, he makes a 50% profit. Anywhere, just about anywhere you can use this percent thing. I think they are going to teach this in our maths class.

Challenge

Tinku’s mother said that he would get a reward if he gets more than 95% marks in the test. He received 46 marks out of 47. His mother now wants to know what percent marks he had. Was it more than 95%?

Solution: Tinku has 46 marks out of 47. That means as a fraction he got 46/47 marks.

46/47 = 4600/47% = 97.87% which is more than 95%.

Supplementary

Joyville bookstore purchased a set of encyclopedia for $2800. They put it up for sale at $4000. No one purchased it. After month, they marked it up by 20% and then placed on sale with a discount of 20%. Someone purchased the set. They figured that they had also incurred an expense of $200 in the whole process. For the sake of keeping records, fill in the following.

Cost (price + expense)………………

Sale price……………….

Discounted sale price…………….

Profit (%)……………….

Answer

Cost (price + expense) $2800 +200 = $3000

Sale price after the mark up $4000 + 4000 x 20 /100 = 4800

Discounted sale price $4800 – 20 x 4800/100 = 3840

Profit (%) ($3840 – 3000) x 100 /3000 = 84000/3000 = 28%