if a number is choosen between 100 and 999 includeing these
numberrs what is the provbabilty that the number selected
does not contain a 7 is

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if a number is choosen between 100 and 999 includeing these numberrs what is the provbabilty that t..

Answer / jamesk

p = prob(1st digit not 7)*prob(2nd digit not 7)*prob(3rd
digit not 7)
=(8/9)*(9/10)*(9/10)
=0.72

Sandhya had it right except that there are 900 numbers
between 100 and 999 inclusive (not 899).

Is This Answer Correct ?    59 Yes 6 No

if a number is choosen between 100 and 999 includeing these numberrs what is the provbabilty that t..

Answer / seiko

no 0f 7's in 100 to 200 is
107,117,127,137,147,157,167,170,171,172,173,174,175,176,177,
178,179,187,197.
so total of 19 numbers between 100 and 199

repeat that for 200-299, 300-399,...,600-699, 800-899, 900-
999, we have 19*8 = 152 occurences

for 700-799, all 100 of them contain a 7

so total numbers contain a 7 is 152 + 100 = 252

total numbers between 100 and 999 is 900

probability = (900-252)/900 = 0.72

Is This Answer Correct ?    51 Yes 8 No

if a number is choosen between 100 and 999 includeing these numberrs what is the provbabilty that t..

Answer / sonjoy

total=900 nos
probability=648/900

Is This Answer Correct ?    20 Yes 4 No

if a number is choosen between 100 and 999 includeing these numberrs what is the provbabilty that t..

Answer / ajeet

100-199------19
similarly for all ranges till 999 except for:

700-799----100

total no.containing 7's= 19*8+100=252

Therefore,

probability=(900-252)/900
= 648/900
= 0.72

Is This Answer Correct ?    10 Yes 3 No

if a number is choosen between 100 and 999 includeing these numberrs what is the provbabilty that t..

Answer / martinzhu

(1-(100+8X19)/900)*100%

Is This Answer Correct ?    5 Yes 2 No

if a number is choosen between 100 and 999 includeing these numberrs what is the provbabilty that t..

Answer / mayank kumar

total numbers between 100 and 999 =900
number that have a digit 7 between 100 and 199 =19
similarly no. that have digit 7 between 200 and 699=5*19
number that have digit 7 between 700 and 799=100
number that have a digit 7 between 800 and 999 =2*19
so total number that have digit seven in them between 100 and 999 are=8*19+100 =252

so numbers that does not have 7 digit in them =900-252 =648

therefore required prob, p =648/900 = 0.72

Is This Answer Correct ?    6 Yes 3 No

if a number is choosen between 100 and 999 includeing these numberrs what is the provbabilty that t..

Answer / shruti

here are 900 numbers between 100 and 999.

those that contain 7 are.....
107, 117, 127, ........ -- 10 of these
207, 217, 227, ........ -- 10 of these too
307, 317, 327, .......
....
9*10 numbers that end in 7.

170, 171, 172, 173, 174, 175, 176, (NOT 177 WE ALREADY COUNTED IT), 178, 179 -- 9 of these
270, 271, 272, 273, 274, 275, 276, (NOT 277 WE ALREADY COUNTED IT), 278, 279 -- 9 of these
...
and so on

so 9*9 numbers that have a middle digit of 7

and finally
700, 701, 702, 703, 704.................., but NOT
(707, 717, 727,....) or (770, 771, 772, 773, ....)

So that's (100 - 10 - 9) = 81 numbers that start with 7.

We had 900 numbers.
N = 900 - 90 - 81 - 81 = 648

So the probability is 648/900 = 0.72

Is This Answer Correct ?    5 Yes 3 No

if a number is choosen between 100 and 999 includeing these numberrs what is the provbabilty that t..

Answer / neha2210

1/10

Is This Answer Correct ?    1 Yes 3 No

if a number is choosen between 100 and 999 includeing these numberrs what is the provbabilty that t..

Answer / neha2210

1/10

Is This Answer Correct ?    1 Yes 3 No

if a number is choosen between 100 and 999 includeing these numberrs what is the provbabilty that t..

Answer / dayquest

total numbers from 100 to 999 = 900

total no of 7's
700 - 799 = 100

70-79 in all 100's except seventh hundred = 90

07,17,27...67,87,97 in
all 100's except seventh hundred = 90

total - 280
probability = (900-280)/900
= 31/45

Is This Answer Correct ?    12 Yes 15 No

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