Someone else created a wallet for me to use. Is this a scam? Someone on social media is offering me to mine bitcoin and they take 10% of any profit I make. I started talking and long story short I was told to download blockchain wallet app. 

They provided me the login credentials and I was told once I login to change my password etc. Does this sound like a scam or legit? I mean about them giving me a user id for a blockchain wallet app and I gotta buy bitcoins, transfer them to this wallet and they will mine bitcoins.

Variant:
The attacker requests that the user creates a new blockchain wallet and then shares the login credentials instead of creating the wallet for the user.
I was told once I login to change my password

It is important you understand why this is a trick intended to deceive you.
Wallets don't contain bitcoin.
Wallets contain a &quot;private key&quot; - it is this private key that gives you control over an amount of bitcoin.
The person who creates a wallet can copy this private key and use it to make a new wallet that has control over the bitcoin. Including control over bitcoin added by you days months or years later.
You changing the password on a wallet does not keep the private key secret and safe if someone else has previously already seen the contents of the wallet.
If it helps, think of the wallet as one of those keysafes with a user-changeable combination to unlock it. If someone has previously  copied the keys inside, changing the combination that opens the keysafe doesn't keep you safe at all.

Keysafe with resettable combination - like a bitcoin wallet. It doesn't contain money. It contains keys that maybe someone already has copies of. Changing the combination on the keysafe (wallet) doesn't make those copies of the keys disappear.

See also
Mining deceptions

I&#39;ve been asked to share wallet credentials to participate in mining. Is that a scam?
Am I Being Prodded By A Bitcoin Mining Scammer?
Mining in the wallet
Blockchain Wallet
How can I get a private key for this address

Wallet deceptions

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