Whisper-20dB Quiet Residence-30dB Soft stereo in Residence-40dB Average Speech-60dB Cafeteria-80dB Pneumatic Jackhammer-90dB Loud crowd noise-100dB Accelerating Bike-100dB Rock concert-120dB Jet Engine (75 ft away)-140dB
(1)Mode=100dB (since 100 is occurring the maximum no. of times, i.e. it has the highest frequency of 2) (2)Mean=sum of observations/Total number of observations =(20+30+40+60+80+90+100+100+120+140)/10 =770/10=10dB (3)Median= 1/2[{n/2}th observation + {(n/2)+1}th observation], where, n=total no. of observations So, 1/2[{10/2}th observation + {(10/2)+1}th observation] =1/2[5th observation+6th observation] =1/2[80+90] [Because:5th observation=80dB and 6th=90dB] =1/2(170) =85 Therefore, median=85dB
