Question
7 children are to be selected from a group of 8 boys and
6 girls. In how many ways will the children with at most 3 girls and at least 4 boys be selected?Solution
Case I:  4 boys and 3 girls can be selected, Number of ways of selection = 8C4 × 6C3 = 70 × 20 = 1400 Case II: 5 boys and 2 girls can be selected, Number of ways of selection = 8C5 × 6C2 = 56 × 15 = 840 Case III: 6 boys and 1 girl can be selected, Number of ways of selection = 8C6 × 6C1 = 28 × 6 = 168 Case IV: 7 boys can be selected, Number of ways of selection = 8C7 = 8 So, total number of ways of selecting the children = 1400 + 840 + 168 + 8 = 2416 ways
Three numbers x, y, and z are co-prime to each other such that xy = 91 and yz = 154. Find the value of (x + y + z).
Find the difference between sum of digits of LCM and HCF of 36, 84 and 132.
If the sum of 2 numbers is 185, their LCM is 1700 and HCF is 5. Then the difference between 2 numbers is:
The LCM of two numbers is 1800 while their HCF is 36. If one of the numbers is 432, then the other number is:
Find the HCF of 244 and 118.
Find the HCF (GCD) of 48 and 72.
Let N be the greatest number that will divide 85, 112, 139 leaving the same remainder in each case. Then sum of the digits in N is:
The LCM and the HCF of the numbers 25 and 50 are in the ratio:
Let N be the greatest number that will divide 85, 116, 147 leaving the same remainder in each case. Then sum of the digits in N is:
The HCF and LCM of two numbers, A and B, are 9 and 162, respectively. The difference between these two numbers is 27. Find their sum.
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