Chapter 13: Ways to Multiply and Divide

Given,

Salary paid to Shantaram for 1 day = Rs 165

So, the salary paid to Shantaram for 28 days = Rs 165 × 28

Hence, the money Shantaram gets in all is Rs 4620.

Thus, the cook will get a salary of Rs 60,225

The salary paid to the minister for 1 day = Rs 195

So, the salary paid to the minister for 365 days = Rs 195 × 365

Hence, the salary of the minister for 1 year is Rs 71,175

And,

The salary paid to the horse rider for 1 day = Rs 95

So, the salary paid to the horse rider for 365 days = 365 × Rs 95

Hence, the salary of the minister for 1 year is Rs 34,675

Years and Years

(a) Sohan drinks 8 glasses of water every day.

• How many glasses will he drink in one month? __________

• How many glasses will he drink in one year?

• If 125 people living in a colony drink 8 glasses of water in a day, how much water will they drink in a year?

The number of glasses of water Sohan drinks everyday = 8

We know that, 1 months – 30 days

So, the number of glasses of water consumed by Sohan = 8 x 30

Hence, Sohan will drink 240 glasses of water in one month.

Now, we know 1 year = 365 days

So, the number of glasses of water consumed by Sohan in 365 days = 365 x 8

Hence, Sohan will drink 2,920 glasses of water in one year.

We have, the number of glasses of water consumed by 1 person for a year = 2,920

So, the number glasses of water consumed by 125 people of the colony for one year = 2920 x 125

Therefore, 125 people of the colony will drink 3, 65,000 glasses of water in one year.

(b) If Soha’s heart beats 72 times in one minute, how many times does it beat in one hour?

• Now find out how many times it beats in one day.

• Count your own heart beats to find out how many times your heart beats in one week.

The number of times Soha’s heart beats in one minute = 72

We know, 1 hour = 60 minutes

So, the number of times Soha’s heart beats in one hour = 72 x 60

Hence, Soha’s heart beats 4,320 times in one hour.

Now, we know one day has 24 hours.

So, the number of times Soha’s heart beats in a day = 4320 x 24

Hence, the number of times Soha’s heart beat in a day is 1, 03,680.

Next,

My heart beats 72 times in a minute. We know, 1 week has 7 days.

So, the number of times my heart beats in one week = 1, 03,680 x 7

Hence, the number times my heart beats in a week is 7, 25,760.

(c) A baby elephant drinks around 12 L of milk every day. How much milk will it drink in two years?

The number of litres of milk the baby elephant drinks in a day = 12 L

We know, number of days in a year = 365

And the number of days in two years = 365 x 2 = 730

So, the number of litres of milk the baby elephant drinks in two years = 12 x 730

Hence, the number of litres of milk the baby elephant will consume in two years is 8,760.

(d) A baby blue whale drinks around 200 L of milk in one day. Just imagine how much milk that is! Find out in how many days your family would use 200 L milk. How much milk would the baby blue whale drink in eight months?

Number of litres of milk a baby blue whale drinks in one day = 200

Number of litres of milk used in my family in one day = 2

So, the number of days for consuming 200 L of milk by my family = 200/2 = 100 days

Now,

We know 1 month = 30 days then, 8 months = 30 x 8 = 240 days

So, the number of litres of milk the baby blue whale will drink in eight months = 200 x 240

Hence, the baby blue whale will consume 48,000 L of milk in eight months.

Karunya – The landlord

Karunya bought three fields.

Dimensions of field (A): Length = 27 m and breadth = 28 m

Area (A) = 27 x 28

Field (A) 756 square metre.

Dimensions of field (B): Length = 36 m and breadth = 12 m

Area (B) = 36 x 12

Field (B) 432 square metre.

Dimensions of field (C): Length = 27 m and breadth = 19 m

Area (C) = 27 x 19

Field (C) 513 square metre.

Cost of 1 square metre of field A = Rs 95

So, the cost of 756 square metre of field A = Rs (756 x 95)

Thus, the cost of field A is Rs 71,820

Cost of 1 square metre of field B = Rs 110

So, the cost of 432 square metre of field B = Rs (432 x 110)

Thus, the cost of field B is Rs 47,520

Cost of 1 square metre of field C = Rs 120

So, the cost of 513 square metre of field C = Rs (756 x 95)

Thus, the cost of field C is Rs 61,560

Now,

The total cost of all the fields = Rs 71,820 + Rs 47,520 + Rs 61,560 = Rs 1, 80,900