Math Logic Time Problem - 1 February

For Solution :

In a modern art gallery, an artist has numerous modern art paintings created by him. He hangs different painting on the space provided to him periodically. When the clock hit 11 am, he hung the painting number 30. When it struck 4 pm, he hung the painting number 240 and when it struck 7:30 pm, he hung painting number 315.Can you determine, which painting number will he hang when the time is 9:20 pm ?