So is बूढ़ा used for people and पुराना used for objects?
Yes that's the general rule. बूढ़ा can also be used for animals.
बूढ़ा शेर - old lion
I thought so. I see that you replied to my question on another exercise too. Your input is helpful, emrys. धन्यवाद!
I made a similar guess and these discussions are very helpful for me as well. Confirmed my guess.
Cars are feminine in hindi, so puranee
Should it not be पुराने since cars are plural?
पुराने is masculine plural form, पुरानी is feminine singular and plural forms.
गाड़ियाँ is a feminine plural noun, hence पुरानी।
Why repeat the same sentences again and again?
Is "These are old cars" correct as well?
No, that'd be ये पुरानी गाड़ियाँ हैं - i.e. the subject becomes 'these', not 'these cars', which changes the word order, as in English.