Three biased coins were tossed 800 times simultaneously. The outcomes are given in the table below partially.

If the occurrence of two heads was thrice that of all heads. Find x.

Options

A. 150
B. 240
C. 300
D. 360

Answer

C

Explanation

Let the frequerncy of all heads be y.
`(x)/(800)=3((y)/(800)),i.e.,x=3y" "(1)`
`120+280+x+y=800,i.e.,x+y=400`
From Eq. `(1)impliesx+(x)/(3)=400` x=300.