what is a phantom read ?

[John B. Matthews]

True. because in the example they are using "INSERT" in transaction
2. surprisingly, Phantom read also called "REPEATABLE READ".

No, phantom read is a potential problem at the REPEATABLE READ
isolation level when a query contains a range in the WHERE clause, e.g.
"BETWEEN 10 AND 30". [1]

Is it because they are not MODIFYING the values but adding some extra
records into it i.e it repeates the values with some additional
records.

No, "This can occur when range locks are not acquired on performing a
SELECT." [2]

True. because in the example they are using "UPDATE" in transaction
2. However,both of them are showing faulty results at the end of
Transaction 1.

At the READ COMMITTED isolation level, "non-repeatable reads may occur
in a lock-based concurrency control method when read locks are not
acquired when performing a SELECT." [4]

The broken link from [3] to [4] has been repaired.

[1]<http://en.wikipedia.org/wiki/Isolation_(database_systems)#REPEATABLE_READ>
[2]<http://en.wikipedia.org/wiki/Isolation_(database_systems)#Repeatable_reads_.28phantom_reads.29>
[3]<http://en.wikipedia.org/wiki/Isolation_(database_systems)#READ_COMMITTED>
[4]<http://en.wikipedia.org/wiki/Isolation_(computer_science)#Read_Committed_.28Non-repeatable_reads.29>

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