Answer:
Step-by-step explanation:
1. Humans can detect sounds in a frequency range from about 20 Hz to 20 kHz.
2. speed of sound is 343 m/sec.
3. two animals are Bats and Whales.
4.The voiced speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz.
So average=(total of scores)/(number of tests)
needs at least average of 70
at least is represented as greater than or equal to or the sign (<u>></u>)
70<u>></u>(total)/(number oftests)
since we have 3 tests, we have to have 3 scores so
70<u>></u>(x+y+z)/3
he scored 85 and 60
70<u>></u>(x+85+60)/3 (doesn't matter which to subsitute)
70<u>></u>(x+145)/3
multiply obht sides by 3
210<u>></u>x+145
subtract 145 from both sides
65<u>></u>x
he needs to get at leas 65 on his third test
2/21 is the answer.
1/3+4/7=19/21
Hope this helps!