Respuesta :
Answer:
35
Step-by-step explanation:
Here we see 5 black keys for every 7 white keys.
So the ratio is 5:7
If we need 49 white keys, find the amount we scale the original ratio by:
49/7 = 7
So we are scaling by a factor of 7.
The number of black keys would be 5 * the scale of 7. = 35
So there should be 35 black keys.
Using proportions, it is found that 35 black keys appear on a portable keyboard with 49 white keys.
- This question is solved by proportions, applying a rule of three.
- The equivalent ratio given, from the picture, is that for 7 white keys, there are 5 black keys. Hence, how many black keys will be there when there are 49 white keys?
The rule of three is:
7 white keys - 5 black keys
49 white keys - x black keys
Applying cross multiplication:
[tex]7x = 49 \times 5[/tex]
Simplifying both sides by 7:
[tex]x = 7 \times 5 = 35[/tex]
Hence, 35 black keys will appear.
A similar problem, also involving proportions, is given at https://brainly.com/question/24372153