Math Part-I - NCERT Solutions - GeniusJnr

Estimate each of the following using general rule:

(a) 730 + 998 (b) 796 − 314 (c) 12, 904 + 2, 888

(d) 28, 292 − 21, 496

Make ten more such examples of addition, subtraction and estimation of their outcome.

The information in which alternative correctly describes the role of RNA in living organisms?

Write the following in decimal form and say what kind of decimal expansion each has:

(i) (ii) (iii)

(iv) (v) (vi)

Two point charges 1 × 10^-8 C and 2 × 10^-8 C are separated by 1 mm in vacuum. Determine the ratio of the magnitudes of the electric fields at the site of the charges.

Make correct statements by filling in the symbols ⊂ or ⊄ in the blank spaces:

(i) {2, 3, 4} … {1, 2, 3, 4, 5}

(ii) {a, b, c} … {b, c, d}

(iii) {x: x is a student of Class XI of your school} … {x: x student of your school}

(iv) {x: x is a circle in the plane} … {x: x is a circle in the same plane with radius 1 unit}

(v) {x: x is a triangle in a plane}…{x: x is a rectangle in the plane}

(vi) {x: x is an equilateral triangle in a plane}… {x: x is a triangle in the same plane}

(vii) {x: x is an even natural number} … {x: x is an integer}

Let f: {1, 3, 4} → {1, 2, 5} and g: {1, 2, 5} → {1, 3} be given by f = {(1, 2), (3, 5), (4, 1)} and g = {(1, 3), (2, 3), (5, 1)}. Write down gof.

Express each of the following integers as a product of its prime factors:
(i) 420
(ii) 468
(iii) 945
(iv) 7325

Express each of the following decimals in the form $\frac{p}{q}:$

(i) 0.39
(ii) 0.750
(iii) 2.15
(iv) 7.010
(v) 9.90
(vi) 1.0001

Find the value of
36 ÷ 6 + 3

Subtract the first rational number from the second in each of the following:
(i) $\frac{3}{8}, \frac{5}{8}$
(ii) $\frac{-7}{9}, \frac{4}{9}$
(iii) $\frac{-2}{11}, \frac{-9}{11}$
(iv) $\frac{11}{13}, \frac{-4}{13}$
(v) $\frac{1}{4}, \frac{-3}{8}$
(vi) $\frac{-2}{3}, \frac{5}{6}$
(vii) $\frac{-6}{7}, \frac{-13}{14}$
(viii) $\frac{-8}{33}, \frac{-7}{22}$

Which of the following are examples of empty set?
(i) Set of all even natural numbers divisible by 5;
(ii) Set of all even prime numbers;
(iii) {x : x² −2 = 0 and x is rational};
(iv) {x : x is a natural number, x < 8 and simultaneously x > 12};
(v) {x : x is a point common to any two parallel lines}.

How many four-digit numbers are there in all?