Depending on breed, management and environment, the domestic horse (including draft horses) today has a life expectancy of 25 to 35 years. It is uncommon, but a few animals live into their 40s and, occasionally, beyond. The oldest verifiable record was Old Billy, a 19th-century horse that lived to the age of 62.
TRUE. Validity is a necessary condition for being sound. 14. FALSE. A valid argument can have a true conclusion and false premises (see #11); and if an argument does not have all true premises, then it is not sound.
1. Reflection of sound waves. If a source of sound is directed at a vertical surface some distance away, an ECHO may be heard. Sound waves bounce off the vertical surface, and are REFLECTED back towards the source. Reflection of sound waves obey the laws of reflection. The human ear cannot distinguish between two sound bursts if they are less than about 0.1 s apart. For that reason, in order to hear an echo, the reflecting object must be more than 17 m away from the hearer (assuming sound travels at 340 mÂ·s-1).