Arjun Suresh (talk | contribs) |
Arjun Suresh (talk | contribs) |
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inclusive) will not contain the digit 7 is: | inclusive) will not contain the digit 7 is: | ||
| − | (a)16/25 (b)(9/10)^3 (c)27/75 '''(d)18/25''' | + | (a)<math>16/25</math> (b)<math>(9/10)^3</math> (c)<math>27/75</math> '''(d)<math>18/25</math>''' |
===Solution=== | ===Solution=== | ||
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{{Template:FBD}} | {{Template:FBD}} | ||
| − | [[Category:Probability]] | + | [[Category:Probability and Combinatorics]] |
[[Category:Questions]] | [[Category:Questions]] | ||
The probability that a number selected at random between 100 and 999 (both inclusive) will not contain the digit 7 is:
(a)<math>16/25</math> (b)<math>(9/10)^3</math> (c)<math>27/75</math> (d)<math>18/25</math>
First digit can be chosen in 8 ways from 1-9 excluding 7 Second digit can be chosen in 9 ways from 0-9 excluding 7 and similarly the third digit in 9 ways. So, total no. of ways excluding 7 = 8*9*9 Total no. of ways including 7 = 9 * 10 * 10 So, ans = (8*9*9)/(9*10*10) = 18/25
The probability that a number selected at random between 100 and 999 (both inclusive) will not contain the digit 7 is:
(a)<math>16/25</math> (b)<math>(9/10)^3</math> (c)<math>27/75</math> (d)<math>18/25</math>
First digit can be chosen in 8 ways from 1-9 excluding 7 Second digit can be chosen in 9 ways from 0-9 excluding 7 and similarly the third digit in 9 ways. So, total no. of ways excluding 7 = 8*9*9 Total no. of ways including 7 = 9 * 10 * 10 So, ans = (8*9*9)/(9*10*10) = 18/25
GATECSE