AI Mentor

Check Your IQ

Free Expert Demo

Try Test

Courses

Dropper NEET Course Dropper JEE Course Class - 12 NEET Course Class - 12 JEE Course Class - 11 NEET Course Class - 11 JEE Course Class - 10 Foundation NEET Course Class - 10 Foundation JEE Course Class - 10 CBSE Course Class - 9 Foundation NEET Course Class - 9 Foundation JEE Course Class -9 CBSE Course Class - 8 CBSE Course Class - 7 CBSE Course Class - 6 CBSE Course

Offline Centres

The mean of 50 observations of a data was 70. At later stage, it is noticed that a value 85 was wrongly read as 60. Find the value of the correct mean.

see full answer

Your Exam Success, Personally Taken Care Of

1:1 expert mentors customize learning to your strength and weaknesses – so you score higher in school , IIT JEE and NEET entrance exams.

An Intiative by Sri Chaitanya

66.7

68.5

70.5

answer is D.

(Unlock A.I Detailed Solution for FREE)

Best Courses for You

JEE

NEET

Foundation JEE

Foundation NEET

CBSE

Detailed Solution

It is given that the mean of 50 observations of a data was 70.
A value 85 was wrongly read as 60.
We have to find the value of correct mean.
Let

x 1, x 2, ...., x n

be the numbers, then mean is given by,

x 1 + x 2 + .... + x n n

Given, mean of 50 observations

= 70

x 1 + x 2 + .... + x 49 + 85 = 3500 x 1 + x 2 + .... + x 49 = 3500 − 85 = 3415

Also,

x 1 + x 2 + .... + x 49 + 60 = 3500 x 1 + x 2 + .... + x 49 = 3500 − 60 = 3440

The difference between the numbers is given by,

= 3440 − 3415 = 25

The new mean is given by,

3500 + 25 50 = 352550 = 70.5

The new mean is 70.5.
Hence, option 4 is correct.

Watch 3-min video & get full concept clarity

courses

No courses found

Result Producing online coaching for JEE/NEET of south India

Largest All India Test Series for JEE/NEET

Best Online Course for IIT JEE

Best Online Course for NEET

Best Online Course for CBSE

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Get Expert Academic Guidance – Connect with a Counselor Today!