Home
Class 12
MATHS
The marks of some students were listed o...

The marks of some students were listed out  of a maximum 75. The SD of marks was found to be 9. Subsequently the marks were raised to a maximum of 100 and variance of new marks was calculated. The new variance is  (1)144   (2) 122   (3)   81   (4)  None of these

A

144

B

122

C

81

D

75

Text Solution

Verified by Experts

The correct Answer is:
A
Promotional Banner

Similar Questions

Explore conceptually related problems

The marks of some students were listed out of a maximum 75. The SD of marks was found to be 9. Subsequently the marks were raised to a maximum of 100 and variance of new marks was calculated. The new variance is 144 2. 122 3. 81 4. 256 5. 16

The marks of 12 students in a Math test are as follows: 8, 10, 4, 8, 5, 6, 9, 7, 6, 8, 9, 10 Find the: a maximum marks, b. minimum marks, c. range of marks, and d. mean marks.

In an experiment with 15 observations of x the following results were available sum x^2=2830 sum x=170 one observation that was 20 was found to be wrong and it was replaced by its correct value of 30 Then the corrected variance is (1) 8.33 (2) 78 (3) 188.66 (4) 177.33

The marks of 9 students in a test were 13,17,20,3,5,3,20,15 and 18. Find quartile deviation.

As part of his discovery of the neutron in 1932, James Chadwick determined the mass of the neutron (newly identified particle) by firing a beam of fast meutrons, all having the same speed, as two different targets and measuing the maximum recoil speeds of the target nuclei. The maximum speed arise when an elastic head-on collision occurs between a neutron and a stationary target nucleus. Represent the masses and final speeds of the two target nuclei as m_(1), v_(1), m_(2) and v_(2) and assume Newtonian mechanics applies. The neutron mass can be calculated from the equation: m_(n) = (m_(1)v_(1) - m_(2)v_(2))/(v_(2) - v_(1)) Chadwick directed a beam of neutrons on paraffin, which contains hydrogen. The maximum speed of the protons ejected was found to be 3.3 xx 10^(7) m//s . A second experiment was performed using neutrons from the same source and nitrogen nuclei as the target. The maximum recoil speed of the nitrogen nuclei was found to be 4.7 xx 10^(6) m//s . The masses of a proton and a nitrogen nucleus were taken as 1u and 14 u , respectively. What was Chadwick's value for the neutron mass?

Means and standard deviations of the scores of an intelligence test of two classes of different sizes of 25 and 75 are M_(1) = 80 marks and M_(2) = 85 marks and SD_(1) = 15 marks and SD_(2) = 20 marks Calculate the combined mean and the standard deviation of the two classes.

All the students of a class performed poorly in Mathematics. The teacher decided to give grace marks of 10 to each of the students. Which of the following statistical measures will not change even after the grace marks were given ? (1) median (2) mode (3) variance (4) mean

The line of regression marks in economics (X) for marks in mathematics (Y) for a class of 50 students is 3y - 5x+180 = 0. Average score in mathematics is 44 and variance of marks in economics is 9/16th , of variance of marks in mathematics. Find the average score in economics and also the coefficient of correlation between marks in economics and mathematics.

Out of 10 students, who appeared in a test, three secured less than 30 marks and 3 secured more than 75 marks. The marks secured by the remaining 4 students are 35, 48, 66 and 40. Find the median score of the whole group.

Out of 10 students, who appeared in a test, three secured less than 30 marks and 3 secured more than 75 marks. The marks secured by the remaining 4 students are 35, 48, 66 and 40. Find the median score of the whole group.