A histogram of puzzle-completion times has the following frequency densities.
time t (s)0≤t<3030≤t<6060≤t<9090≤t<120120≤t<150frequency density11486\begin{array}{c|ccccc}\text{time }t\text{ (s)}&0\leq t<30&30\leq t<60&60\leq t<90&90\leq t<120&120\leq t<150\\\hline\text{frequency density}&1&1&4&8&6\end{array}time t (s)frequency density0≤t<30130≤t<60160≤t<90490≤t<1208120≤t<1506
There are 120 people with completion time at least 150 seconds. Estimate the percentage who took less than 90 seconds.