If (L)M represents a number L in base-M number system, then identify the…

2024

If (L)M represents a number L in base-M number system, then identify the correct descending order of the following numbers A-D when converted to decimal number system.

(A) (10110.11)2

(B) (110.2)4

(C) (32.5)8

(D) (14.6)16

Choose the correct answer from the options given below :

Answer: A. (C), (A), (B), (D)Concept — positional weights in any base In a base-b positional system each digit is weighted by a power of the base fixed by its position. Reading outward…

  1. A.

    (C), (A), (B), (D)

  2. B.

    (C), (B), (D), (A)

  3. C.

    (A), (C), (D), (B)

  4. D.

    (B), (C), (A), (D)

Attempted by 10 students.

Show answer & explanation

Correct answer: A

Concept — positional weights in any base

In a base-b positional system each digit is weighted by a power of the base fixed by its position. Reading outward from the radix point in either direction, the digits on its left carry the weights b0, b1, b2, … and the digits on its right carry b-1, b-2, …, so a numeral (dk…d1d0.f1f2)b equals the sum of every di·bi plus the sum of every fj / bj. Numerals written in different bases carry no common scale, so they can only be ranked after each one is re-expressed in a single shared base; decimal is the standard bridge for that.

Application — convert each numeral to decimal

  1. (10110.11)2 = (1·16 + 0·8 + 1·4 + 1·2 + 0·1) + (1/2 + 1/4) = 22 + 0.75 = 22.75

  2. (110.2)4 = (1·16 + 1·4 + 0·1) + (2/4) = 20 + 0.5 = 20.5

  3. (32.5)8 = (3·8 + 2·1) + (5/8) = 26 + 0.625 = 26.625

  4. (14.6)16 = (1·16 + 4·1) + (6/16) = 20 + 0.375 = 20.375

Cross-check — rank the decimal values

Numeral

Label

Decimal value

(32.5)8

C

26.625

(10110.11)2

A

22.75

(110.2)4

B

20.5

(14.6)16

D

20.375

Ranking those decimal values from largest to smallest gives 26.625 > 22.75 > 20.5 > 20.375. The bottom two share the same integer part 20, so their fractional parts alone separate them: 2/4 = 0.5 exceeds 6/16 = 0.375. Reading the labels off that ranking, the descending order of the four numerals is (C), (A), (B), (D).

Explore the full course: Nta Ugc Net Paper 1

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