Let the length of the shortest piece be x cm. Then, second length `=(x+3)` cm and third length `= 2x ` cm.
`thereforex +(x+3)+2xle91]and 2xge(x+3)+5`
`rArr 4x+3le91 and2xgex+8`
`rArr 4x le91-3and 2x-xge8`
`rArr 4x le88 and x ge8`
`rArrx le22 and x ge 8`
`rArrx le22 and x ge 8`
Hence, the length of the shortest piece is to be greater than or equal to 8 but less than to 22.