Banner 0
Banner 1
Banner 2
Banner 3
Banner 4
Banner 5
Banner 6
Banner 7
Banner 8
Banner 9

Q.

Let A be a set of all 4 –digit natural numbers whose exactly one digit is 7. Then the probability that a randomly chosen element of A leaves remainder 2 when divided by 5 is

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

a

97297

b

15

c

29

d

122297

answer is A.

(Unlock A.I Detailed Solution for FREE)

Best Courses for You

JEE

JEE

NEET

NEET

Foundation JEE

Foundation JEE

Foundation NEET

Foundation NEET

CBSE

CBSE

Detailed Solution

The number of four digit numbers having 7 as one digit in that four

 

If the number begins with 7, then the number of four-digit numbers is 1×9×9×9

 

The number of four-digit numbers, in which 7 is not in the first place and 7 must be one of the digits in the remaining three digits, is 8×3C1×9×9

Hence the total number four-digit numbers having 7 as one of the digits isn(s)=9×9×9+24×9×9=81×(33)=2673

Among all the above numbers, find the number of numbers whose unit digit is either 2 or 7

 

The number of four-digit numbers having 2 as unit digit and 7 as first digit is 81, the number of four digit numbers having 7 in unit digit is   8×9×9=648

And the number of four-digit numbers having 2 as unit digit and 7 at any place other than first digit place is 8×2C1×9=144

The number of four-digit numbers whose unit digit is either 2 or 7 isnA=81+648+144=873

 

Therefore, the required probability is nAnS=8732673=97297

Watch 3-min video & get full concept clarity
score_test_img

courses

No courses found

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!

best study material, now at your finger tips!

  • promsvg

    live classes

  • promsvg

    progress tracking

  • promsvg

    24x7 mentored guidance

  • promsvg

    study plan analysis

download the app

gplay
mentor

Download the App

gplay
whats app icon
personalised 1:1 online tutoring