Question

Diana had a large stack of playing cards. She knew that 17 of them were kings. She took a sample of 30 cards and found 4 kings. Approximately how many playing card did Diana have?

Answer 1

Answer:

Diana approximately had 128 cards

Step-by-step explanation:

Let n  be the number of cards Diana had. She knows that

• there are 17 kings among n cards
• 4 kings among 30 cards

Write a proportion:

$\dfrac{17}{n}=\dfrac{4}{30}$

Cross multiply:

$4n=17\cdot 30\\ \\4n=510\\ \\n=\dfrac{510}{4}=127.5\approx 128$