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Real Numbers

Question
CBSEENMA10006253

Three sets of Physics, Chemistry and Biology books have to be stacked in such a way that all the books are stored topic-wise and the height of each stack is the same. The number of Physics books is 105, the number of Chemistry books is 140 and the number of Biology books is 175. Assuming that the books are of the same thickness, determine the number of stacks of Physics, Chemistry and Biology books.

Solution

 In order to arrange the books as required, we have to find the largest number that divides 105, 140 and 175 exactly.

Clearly, required number is the HCF of 105, 140 and 175.

Case I :

I. Finding HCF of 105 and 140 by applying Euclid’s division lemma, we get

II. Since, the remainder 35 ≠ 0, we apply division lemma to get

Since, the remainder at this stage is zero, so the divisor i.e., 35 at this stage is the HCF of 105 and 140.

Case II :

I. Finding the HCF of 35 and 175 by applying Euclid’s division lemma, we get

II. Since the remainder at this stage is zero, so the divisor i.e., 35 at this stage is the HCF of 35 and 175.

Thus, HCF of 105, 140) and 175 is 35.

Now,

Number of stacks of Physics books
equals fraction numerator Number space of space Physics space books over denominator NMumber space of space books space in space each space stack end fraction
equals space 105 over 35 equals 3
Number of stacks of Chemistry books
equals fraction numerator Number space of space Chemistry space books over denominator Number space of space books space ineach space stack end fraction

equals 140 over 35 equals 4
Number of stacks of Biology books
equals fraction numerator Number space of space Biology space books over denominator Number space of space books space in space each space stack end fraction

equals 175 over 35 equals 5.