Mentally estimate the total cost of item that have the following prices 1.85, 0.98,3.49,9.78,6.18 .round off your answers to the nearest half-dollar.

Total cost of items is $22.5.

Step-by-step explanation:

Rounding off is a kind of estimating. When the number after decimal is less than 5, the last figure should be unchanged, but the number after decimal is 5 or more than 5 add one to the last digit.

1.85 ≈ 2

0.98 ≈ 1

3.49 ≈ 3.5

9.78 ≈ 10

6.18 ≈ 6

Total cost of items = 2 + 1 + 3.5 + 10 + 6 = $22.5

e^-kt = n/n0 = 0.79  

-kt = ln 0.79  

t = - ln 0.79/0.0001  

= 2357 years

step-by-step explanation:

umm im not really sure because i never had to do this

step-by-step explanation: