EX.3.7 PROBLEM SUMS (POST 1)

Word Problems 1 (playing with numbers)

April 26, 2020

Good morning students !😊😊

Welcome to mathematics blog lesson.

Topic is -"Playing with numbers"

➧Copy the Points to remember and Key words for HCF & LCM word problems in your MATHS NOTEBOOK

Applications of LCM and HCF

As you know, Maths is a subject you understand, not a subject you memorize. So learning the application of a concept helps you fully understand the topic, and also makes it interesting. There are various interesting applications of L.C.M and H.C.F. Let us learn more about them.

Points to remember while solving H.C.F/G.C.F and L.C.M word problems
(WRITE ALL THE POINTS GIVEN BELOW IN YOUR NOTEBOOK)

➤Whenever the question talks about the greatest or maximum, then in most of these cases it will be a question of HCF. Secondly, whenever the question is related to classification or distribution into groups, then in all the cases it is HCF only.

➤when a number divides (means a number is a divisor), it is of H.C.F only.

➤Whenever the question talks about the smallest or minimum, then in most of the cases it will be a question of LCM. Secondly, whenever the word ‘together’ or ‘simultaneous’ is used in the question, then in all the cases it is LCM.

➤when a number is divisible (means a number is dividend), it is of L.C.M only

In Case Of H.C.F/G.C.F

➨If some remainders are given, then firstly those remainders are subtracted from the numbers given and then their HCF is calculated.

In Case Of L.C.M

➨ If a single remainder is given, then firstly the LCM is calculated and then that single reminder is added in that.

➨ If for different numbers different remainders are given, then the difference between the number and its respective remainder will be equal. In that case, firstly the LCM is calculated, then that common difference between the number and its respective remainder is subtracted from that.

KEYWORDS FOR H.C.F & L.C.M WORD PROBLEMS

To understand it in a better way, let’s watch a video or click on the link-https://youtu.be/KgZ-GbtCLu0

Don’t think that you will be able to understand it in a day…. It will take time…the more you practice the more you will be confident about its usage!!

Let's Start Ex-3.7 (page no.67) ( Do them in your MATHS NOTEBOOK)

Q1: Renu purchases two bags of fertilizers of weights 75 kg and 69 kg. Find the maximum value of weight which can measure the weight of the fertilizer exact number of times.

Solution: Weight of two bags= 75 kg and 69 kg

Maximum value of weight = HCF of 75 and 69

Prime Factorisation of 75 = 3 × 5 × 5

Prime Factorisation of 69 = 3 × 23

Here, the common factor is 3.

∴ HCF of 75 and 69 = 3

Hence, maximum value of weight which can measure the weight of the fertiliser exact number of times (means a divisor) = 3 kg.

Q2: Three boys step off together from the same spot. Their steps measure 63 cm, 70 cm and 77 cm respectively. What is the minimum distance each should cover so that all can cover the distance in complete steps?

Solution: Minimum distance = LCM of 63, 70, 77

∴ LCM of 63, 70 and 77 = 2 x 3 x 3 x 5 x 7 x 11 = 6930

Hence, the minimum distance each boy should cover so that all can cover the distance in complete steps (finding something that happens at the same time)= 6930 cm.

HOMEWORK

Try to answer this question👇

Q: Lenin is preparing dinner plates. He has 12 pieces of chicken and 16 rolls. If he wants to make all the plates identical without any food left over, what is the greatest number of plates Lenin can prepare? (Hint- the content in Red).

  That's all for today.

       

       Take care.

       GOD BLESS !!