20 Din Aise Bhautiki Vigyan Padh Lia to Laoge 90 Plus Marks | Strategy | Doubtnut

A teacher wanted to analysis the performance of two sections of students in a mathematics test of 100 marks. Looking performance, she found that a few students got under 20 marks and a few got 70 marks or above. So she decided to group them into intervals of varying sizes as follows : 0-20, 20-30, ....., 60-70, 70-100. Then she formed the following table : |{:("Marks"," Number of students"),(0-20," 7"),(20-30," 10"),(30-40," 10"),(40-50," 20"),(50-60," 20"),(60-70," 15"),(70-"above"," 8"),("Total"," 90"):}| (i) Find the probability that a student obtained less than 20% in the mathematics test. (ii) Find the probability that a student obtained marks 60 or above .

Following table shows the marks scored by a group of 90 students in a mathematics test of 100 marks. Marks 0-20 20-30 30-40 40-50 50-60 60-70 70-100 No. of Students: 7 10 10 20 20 15 8 Find the probability that marks scored by a student in the class is: at most 60 marks (ii) at least 60 marks (iii)not more than 50 marks

(i)Find the class mark of the class 90-120. (ii)In a frequency distribution, the mid-value of the class is 10 and width of the class is 6. Find the lowe limit of the class. (iii)The width of each of the five continuous classes in a frequency distribution is 5 and lowe class limit of the lowest class is 10. What is the upper class limit of the highest class? (iv) The class marks of a frequency distribution are 15,20,25...... Find the class corresponding to the class mark 20. (v)In the class intervals 10-20, 20-30, find the class in which 20 is included.

A meter stick is hung from two spring balances A and B of equal lengths that are located at the 20 cm and 70 cm marks of the meter stick. Weights of 2.0N are placed at the 10cm and 40cm marks, while a weight of 1.0N is placed at the 90cm mark. The weight of the uniform meter stick is 1.5 N. Determine the scale readings of the two balances A and B.

In a History examination,the average for the entire class was 80 marks.If 10% of the students scored 95 marks and 20% scored 90 marks,what was the average marks of the remaining students of the class? 65.5 b.72.5 c.75 d.85

The marks obtained by 90 students of a school in mathematics out of 100 are given as under : From these students , a student is chosen at random . What is the probability that the chosen student (i) gets 20% or less marks ? (ii) gets 60% or more marks ?

Consider the marks, out of 100, obtained by 51 students of a class in a test, given in Table 14.9. M a r k s"N u m b e r o f S t u d e n t s"0-10 5 10-20 10 20-30 4 30-40 6 40-50 7 50-60 3 60-70 2 70-80 2 80-90 3 90-100 9Tot a l 51 Draw a freque