1.

Give the answer in scientific notation:A human heart beats at an average of 80 beats per minute. How many times does it beat in(i) an hour?(ii) a day?(iii) a year?(iv) 100 years?

Answer»

Heart beat per minute = 80 beats

(i) an hour One hour = 60 minutes

Heart beat in an hour = 60 x 80 = 4800 = 4.8 x 10

(ii) In a day

One day = 24 hours = 24 x 60 minutes

∴ Heart beat in one day = 24 x 60 x 80 = 24 x 4800 = 115200 = 1.152 x 105

(iii) a year

One year = 365 days = 365 x 24 hours = 365 x 24 x 60 minutes

∴ Heart beats in a year = 365 x 24 x 60 x 80 = 42048000 = 4.2048 x 107

(iv) 100 years

Heart beats in one year = 4.2048 x 107

Heart beats in 100 years = 4.2048 x 107 x 100 = 4.2048 x 107 x 102

= 4.2048 x 109



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