Correct Answer - `8`
`|(dN)/(dt)|=lambdaN_(0)e^(-lambdat) :. ln |(dN)/(dt)|=ln(N_(0)lambda)-lambdat`
`:. ln |(dN)/(dt)|=ln (N_(0)lambda)-lambdatimplies -lambda=` slope `=-1/2year^(-1)`
`implies lambda=1/2 yr^(-1)`
`:. t_(1//2)=0.693/lambda=1.386` given time is `3` times of `t_(1//2)`
`:.` value of p is 8.