Maths Science

LCM of x and y = 161 x × y = 161 = 23 × 7 Now, x = 23 and y = 7 Then, 3y – x = 3 × 7 – 23 = 21 – 23 = – 2

In standard form = 8·2903 × 108 Now, here k = 8·2903 and n = 8 Then, k + n = 8·2903 + 8 = 16·2903

Let a = – 3, b = – 2, c = – 1 Then, a + c < b – 3 – 1 < – 2 – 4 < – 2

Required number = – 5/7 – (– 1) = – 5/7 + 1 = 2/7

–11/20 = –0·55, 7/–15 = –0·46 17/–30 = –0·56 –3/10 = –0·3 In descending order— –3/10 > 7/–15 > –11/20 > 17/–30

Purchased price = 145800 × 100 × 100 × 100 / 90 × 90 × 90 = Rs 2,00,000

Cost price of 20 articles = Selling price of x articles. Then, profit percentage = (20 – x) / x × 100 25 = (20 – x) / x × 100 x = 80 – 4x ⇒ 5x = 80 x = 16

Geo Gebra is an interactive geometry, algebra, statistics and calculus application, intended for learning and teaching mathematics and science from primary school to university level. Geo Gebra is available on multiple platforms with its desktop applications for Windows, Mac OS and Linux, with its tablet apps for Android, iPad and Windows, and with its web application based on HTML5 technology.

The National Curriculum Framework (NCF 2005) is one of four National Curriculum Frameworks published in 1975, 1988, 2000 and 2005 by the National Council of Educational Research and Training (NCERT).

Required probability = 7 / 12

Let number of sides of the polygon = n. Then, (n – 2) × 180 = 1440 n – 2 = 8 n = 10

Let side of the square = a and, diameter of the circle = 2r Then, a2 = 16/x × π r2 a2 = 16r2 a/r = 4 a/2r = 2 Hence, required ratio = 2 : 1.

Let B’s money = 100 Then, A = 120 and C = 80 Now, Required per cent = 120 – 80/80 × 100 = 40/80 × 100 = 50%

Age of Hamid = (y – x) Then, 15 years ago, y – x – 15 = (y – 15) ×1/4 4y – 4x – 60 = y – 15 3y – 4x = 45

Let hundred place values 7, 8 or 9 Then, unit place value unit 0 for 7, 1 for 8 and 2 for 9 real number – 700, 801, 902 On changing the order – 007/693, –108/693, –209/693 Hence, unit digit of the final number is 3.

The NCF 2005 document draws its policy basis from earlier government reports on education as Learning Without Burden and National Policy of Education 1986 1992 and focus group discussion.

Let radius of a cylinder = r cm. Then, 4 × 2π r h = 2π r2 × 6 4 × 12 = r × 6 r = 8 cm Hence, volume of a cylinder = π r2h = π (8)2 × 12 = 768 π cm3

David John Wheeler was a computer scientist. Wheeler’s contributions to the field included work on the EDSAC and the Burrows-Wheeler transform.

Required angle = 90 + 130/2 = 90 + 65 = 155°

A sea breeze is a gentle wind that develops over bodies of water near land due to differences in air pressure created by their different heat capacity. It is a common occurrence along coasts during the morning as solar radiation heats the land more quickly than the water.

Litmus is a water-soluble mixture of different dyes extracted from lichens, especially Roccella tinctoria. It is often absorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity.

Constructivism is a theory of knowledge that argues that humans generate knowledge and meaning from an interaction between their experiences and their ideas. Piaget’s theory of constructivist learning has had wide ranging impact on learning theories and teaching methods in education and is an underlying theme of many education reform movements.

A pinhole camera is a simple camera without a lens and with a single small aperture, a pinhole— effectively a light-proof box with a small hole in one side. Light from a scene passes through this single point and projects an inverted image on the opposite side of the box.

The thyroid gland is one of the largest endocrine glands and consists of two connected lobes. The thyroid gland is found in the neck, below the thyroid cartilage. The thyroid gland controls how quickly the body uses energy, makes proteins, and controls how sensitive the body is to other hormones.

Fraction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.

LPG is prepared by refining petroleum or ‘wet’ natural gas, and is almost entirely derived from fossil fuel sources, being manufactured during the refining of petroleum (crude oil), or extracted from petroleum or natural gas streams as they emerge from the ground.

Iodine and its compounds are primarily used in nutrition, and industrially in the produc-tion of acetic acid and certain polymers. Iodine’s relatively high atomic number, low toxicity, and ease of attachment to organic compounds have made it a part of many Xray contrast materials in modern medicine. Iodine has only one stable isotope. A number of iodine radioisotopes are also used in medical applications.

The pancreas is a glandular organ in the digestive system and endocrine system of vertebrates. In humans, it is located in the abdominal cavity behind the stomach. It is an endocrine gland producing several important hormones, including insulin, glucagon, somatostatin, and pancreatic polypeptide which circulate in the blood. The pancreas is also a digestive organ, secreting pancreatic juice containing digestive enzymes that assist digestion and absorption of nutrients in the small intestine.

Starfish are marine invertebrates. They typically have a central disc and five arms, though some species have more than this. The amoral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates.

The approach and recommendations of NCF-2005 are for the entire educational system. A number of its recommendations, for example, focus on rural schools. The syllabus and textbooks based on it are being used by all the CBSE schools.