NCERT 2022 | दहन और ज्वाला - L2 | Combustion and Flame | CLASS 8 विज्ञान | 7 PM Class by Amba Mam

Ratio of the fares of First ,Second and Third class catogory of a train , between two stations is 10:7:2 and the ratio of passenger travelling in these category is 4:9:17 respectively .If the fare is increased by 1/4 in First class , 1/8 in second class and decreased by 10% i Third Class and the ratio of number of passenger in the category remains same .If the total amount received of Rs. 60590 , then find the total amount received from thrid class category .

The marks obtained by 40 students of class IX in an examination are given below: 18, 8, 12, 6, 8, 16, 12, 5, 23, 2, 16, 23, 2, 10, 20, 12, 9, 7, 6, 5, 3, 5, 13, 21, 13, 15, 20, 24, 1, 7, 21, 16, 13, 18, 23, 7, 3, 18, 17, 16 Present the data in the form of a frequency distribution using the same class size, one such class being 15-20 (where 20 is not included)

The marks obtained by 40 students of class VIII in an examination are given below: 18,8,12,0,8,16,12,5,23,2,16,23,2,10,20,12,9,7,6,5,3,5, 13,21,13,15,20,24,1,7,21,16,13,18,23,7,3,18,17,16 Present the data in the form of a frequency distribution using the same class size, one such class being 15-20 (where 20 is not included).

Thirty children were asked about the number of hours they watched TV programmes in the previous week. The results were found as follows: 1 6 2 3 5 12 5 8 4 8 10 3 4 12 2 8 15 1 17 6 3 2 8 5 9 6 8 7 14 12 (i) Make a grouped frequency distribution table for this data, taking class width 5 and one of the class intervals as 5 - 10. (ii) How many children watched television for 15 or more hours a week?

Calculate the heat produced when 3.785 litre of actane (C_(8)H_(18)) reacts with oxygen to form CO & water vapour at 25^(@)C . The density of octane is 0.7025 gm/ml. enthalpy of combustion of C_(8)H_(18) is -1302.7 k Cal/mol. {:(DeltaH_(f)^(@) CO_(2)(g)=-94.05" k Cal mol"^(-1),,,DeltaH_(f)^(@) CO(g)=-26.41" k Cal mol"^(-1),),(DeltaH_(f)^(@) H_(2)O(l)=-68.32" k Cal mol"^(-1),,,DeltaH_(f)^(@) H_(2)O (g)=-57.79" k Cal mol"^(-1)):}

The following data : 2, 5, 15, 25, 20, 12, 8, 7, 6, 16, 21,17, 30, 32, 23, 40, 51, 15, 2, 9, 57, 19, 25 is grouped in the classes 0 –5, 5 –10, 10 –15 etc. Find the frequency of the class 20 –25.

Following are the number of members in 25 families of a village: 6, 8, 7, 7, 6, 5, 3, 2, 5, 6, 8, 7, 7, 4, 3, 6, 6, 6, 7, 5, 4, 3, 3, 2, 5. Prepare a frequency distribution table for the data using class intervals 0-2, 2-4, etc.

The ratio of the number of boys in sections A and B of a class is 2 : 3 and the ratio between the total number of boys and girls in sections A and B is 3 : 4. If the number of girls in B is 50% of the number of boys in B, then what will be the ratio between the number of girls in A and B ? एक कक्षा के अनुभाग A और B में लड़कों की संख्या का अनुपात 2:3 है तथा अनुभाग A और B में लड़कों और लड़कियों की कुल संख्या का अनुपात 3:4 है | यदि 8 में लड़कियों की संख्या, B में लड़कों की संख्या की 50% है, तो A और B में लड़कियों की संख्या का अनुपात कितना होगा ?

The distance (in km) of 40 engineers from their residence to their place of work were found as follows: 5 3 10 20 25 11 13 7 12 31 19 10 12 17 18 11 32 17 16 2 7 9 7 8 3 5 12 15 18 3 12 14 2 9 6 15 15 7 6 12 Construct a grouped frequency distribution table with class size 5 for the data given above taking the first interval as 0-5 (5 not included). What main features do you observe from this tabular representation?

Directions (Questions 519 to 523): These questions are based on the following information: Children in a class play only one or two or all of the three games – badminton, football and cricket. 5 children play only cricket, 8 children play only football and 7 children play only badminton. 3 children play only two games – badminton and football, 4 children play only 2 games cricket and football, and another 4 children play only two games – badminton and cricket. 2 children play all the three games. How many children play football as well as cricket? (a) 4 (b) 6 (c) 7 (d) 15 (e) None of these