please help me by solving these problems:part-3

[prithibi]

to gmm21
explanation: 5^9 has 5 at ones place and 7^10 has 9 at ones place. by adding those two we get 14 i.e. 4 which is even number. and we know even number is always divided by 2. col A produces 2. and the answer is (B)

[sandipank]

Originally Posted by prithibi

16. answer :3/16
i found this which does not match with the alternatives provided. can any one explain the prblm and answer.

Can you plz explain the method???

[taminkeu]

chestnut
5^9 +7^10 is divible by 2 answer is therefore B

[julle286]

Could someone please explain the solution of question 3 ... ?

And what about 5?

[chestnut.cc]

yeah thats correct... my bad... B... :s

[hiebiz]

How to solve this problem?

John wrote a phone number on a note that was later lost. John can remember that the number had 7 digits, the digit "1" appeared in the last three places and "0" did not appear at all. What is the probability that the phone number contains at least two prime digits?
a) 15/16 b) 11/16 c) 11/12 d) 1/2 e) 5/8

[pavanireddy]

hi culd u please explain as to how did u get the first ans as D as there is no option mentioned

[prithibi]

i need explanation of prblm # 1, 4 and 10

[chestnut.cc]

1.The ans to the first sum cannot be determined by the data... the set of nos can be arbitrarily wide or close...

4. The radii of the concentric circles not being given... one cannot determine the probability of selecting a point in the region betn the circles which can be made arbitrarily large or small as we increase the radii of the large circle..

10. Interpreting this sum as (10^50)*(m+h)... the remainder when m+h is divided by 9 must be zero if the data is to be consistent... B