Chapter lcm and hcf for all competitive exams part 2

The ratio of LCM and HCF of the least composite and the least prime numbers is (a) "1:2," (b) "2:1.," (c) "1:1.," (d) "1:3"

Professors Lambert and Stassen teamteach an advanced psychology class. Their students recently took their final exams, and the professors are preparing to grade them. Professor Stassen predicts that, if she graded all the exams, she would take 50% more time than Professor Lambert would if he graded all the exams. They estimate that it will take them 40 hours to grade all the exams if they grade together. Which of the following equations best represents the situation described?

Can two numbers have 15 as their H.C.F. and 110 as their L.C.M.? Give reason to justify your answer.

Can two numbers have 12 as their H.C.F. and 234 as their L.C.M? Give reason to justify your answer.

A certain exam lasts a total of 4 hours. Each part of the exam required the same amount of time and 10 minute brekas are included between consecutive parts. If there is a total of 4 breaks during the 4 hours, what is the required time, in minutes, for each part of the test?

Find the HCF and LCM of the following pairs using prime factorisation method: (i) 140 and 154 (ii) 504 and 735

The LCM and HCF of two rational numbers are equal, then the numbers must be (a) prime (b) co-prime (c) composite (d) equal

The HCF and LCM of two numbers are 18 and 720 respectively. Find the product of two numbers.

Find the HCF and LCM of the following by prime factorisation method : (i) 12,18,24 (ii) 15,25,45

Find the HCF and LCM of the following by prime factorisation method : (i) 12 and 15 (ii) 20 and 25 (iii) 28 and 42