The table shows the battery life of four different mobile phones: Mobile Phone Battery Life Phone
Battery Life (hours)
A 20
B 25
C 10
D 18
If 8.45% of the battery life of each mobile phone is used in a day by a typical user, which mobile phone would use a total of 1.69 hours of battery life in a day?
Phone A
Phone B
Phone C
Phone D

Using quick mental math, we can do 8% of 10 to get 0.8, which is close to the value of 0.0845*10. Also fairly quick is moving the decimal point over 1 spot to the right and we go from 0.0845 to 0.845 and that rounds to 0.8 when rounding to one decimal place. Recall that 8.45% = (8.45/100) = 0.0845

If you want to compute out the four results with a calculator, then it would look like this:

0.0845*20 = 1.69

0.0845*25 = 2.1125

0.0845*10 = 0.845

0.0845*18 = 1.521

and this shows that no other result (but choice C) is close to 0.8

So that's why the answer is choice C

Step-by-step explanation:

c.   x=2.4cm

step-by-step explanation:

similar triangles are triangles which have the same shape but not the same size. this means their angle measures are equal but their side lengths are not instead they are proportional. to solve, we will set up a proportion and solve.

a proportion is two equal ratios set equal to each other. we form the ratios by finding corresponding sides (sides which match to each other on both triangles by their position). out ratios will be one side of the small triangle over the corresponding side on the big triangle as shown below:

.

to solve the proportion, we'll cross multiply by multiplying numerator with denominator across the equal sign.