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 :(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 . 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"):}|

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 .

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

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.

Fig.1.33 shows a uniform metre rule placed on a fulcrum at its mid point O and having a weight 40gf at the 10cm mark and a weight of 20gf at the 90cm mark. (i) Is the metre rule in equilibrium? If not , how will the turn? (ii) How can the rule be brought in equilibrium by using an additional weight of 40 gf?

In an examination, 20% of the students scored 70 marks, 40% scored 80 marks, 30% scored 90 marks and the rest scored 100 marks. Then the mean score of the students is