David had 20 pencils.5 of them are green and 15 are purple. What percentage of pencils were green?

25%

Step-by-step explanation: Since we know that David has 20 pencils in all and that 5 of the pencils he has are green, we have the fraction 5/20 which represents the 5 green pencils out of all of his pencils.

Now, remember the problem is looking for a percent so we need to write 5/20 as a percent in order to answer the question.

To write a fraction as a percent, first remember that a percent is a ratio of a number to 100. So to write 5/20 as a percent, we need to find a fraction equivalent to 5/20 that has a 100 in the denominator. We can do this by setting up a proportion.

Now, we can use cross products to find the missing value.

So we have 5 times 100 which is 500 is equal to 20 times n or 20n.

So we have 500 = 20n.

Now, dividing both sides of the equation by 20, we have 25 = n.

So 5/20 is equal to 25/100 or 25%.

Therefore, 25% of David's pencils are green.

16.9 times 2.85

step-by-step explanation:

b. 6

step-by-step explanation:

we are given the table representing an exponential function.

we can see from the table that, as x is increasing, the value of y is increasing in the power of 6.

i.e. the following relation is obtained,

x = 1, y = 6

x = 2, y = 36 =

x = 3, y = 216 =

x = 4, y = 1296 =

x = 5, y = 7776 =

so, the geometric series obtained is .

thus, the common ratio is given by = = 6.

hence, the common ratio is 6.