21.

Which of the following options does not demonstrate the achievement of skill objectives of teaching, school mathematics in upper primary stages?

• The pupil handles geometrical instruments with ease and proficiency

• The pupil measures accurately

• The pupil solves routine type of problems using a formula

• The pupil does written calculation with ease and speed

X runs twice as fast as Y and Y runs thrice as fast as Z. The distance covered by Zin 72 min, will be covered by X

• 24min

• 18min

• 16min

• 12min

The given Pie-chart shows the marks scored by a student in different subjects in an examination. If the total marks obtained by the student be 648, then marks scored in English, Science and Social Science exceed the marks scored in Hindi and Mathematics by

• 66

• 54

• 48

• 30

The mean of n observations is m,. If m² - m + 1 is added to each observation, what will be the value of new mean ?

• m² - 1

• m² - 2m + 1

• $\frac{{\mathrm{m}}^2 + 1}{\mathrm{n}}$

• 1 + m²

$\mathrm{If} (3\mathrm{a} + 5\mathrm{b}) : (3\mathrm{a} - 5\mathrm{b}) = 5 : 1, \mathrm{then} \mathrm{the} \mathrm{value} \mathrm{ofa} : \mathrm{b} \mathrm{will} \mathrm{be}$

• 3 : 2

• 5 : 3

• 2 : 1

• 5 : 2

The production of company X is 120% of the production of company Y and 80% of the production of company Z. The respective ratio between the production of companies X, Y and Z is

• 4 : 3 : 5

• 6 : 5 : 9

• 10 : 9 : 12

• 12 : 10 : 15

"In a triangle, if two sides are equal, then the angles opposite to equal sides have equal measures." The inverse of this theorem will be

• In a triangle, if the angles opposite to two sides have equal measures, then the two sides are equal

• In a triangle, if two sides are not equal, then the angles opposite to these two sides do not have equal measures

• In a triangle, if its measures of angles opposite to two sides are not equal, then the two sides are not equal

• All of the above

A shopkeeper sells 25 books at the rate of Rs 45 per book after giving 10% discount and gain 50% profit. If the discount is not given, then profit per cent will be

• 60

• 66

• $66\frac{1}{3}$

• $66\frac{2}{3}$

Three numbers are in the ratio of 3:4:5 and their LCM is 2400. Their HCF is

• 24

• 36

• 40

• 60

In reference to difference between teaching of Mathematics and teaching of Science, the wrong statement is

• Teaching of mathematics starts with well defined terms, axioms, theorems while teaching of science starts with evidence and explanations.

• Teaching of science involves only deductive process while teaching of mathematics involves a combination of both inductive and deductive processes

• Mathematics is a man-made universe while Science is a natural one

• In teaching of science, the results are validated through experiments, in teaching of mathematics experimentations are the means to verify some of the probable results