Answer:
a) 5 : 7
b) 25 black keys
c) 100 black keys will appear.
Explanation:
a) From the picture,
There are 5 black keys and 7 white keys.
Therefore, the ratio of black keys to white keys are = 5 : 7 = 5/7
b) If the pattern continues, 25 black keys will be appeared on a portable full-sized keyboard.
Explanation -
From part A, we get the ratio of black keys to white keys = 5 : 7. Therefore,
If there are 7 white keys, there are 5 black keys
If there are 1 white keys, there are 5/7 black keys
If there are 35 white keys, there are (5*35)/7 black keys
= 25 black keys.
c) If there are 240 keys, the black keys will appear -
We get, the ratio of black keys to white keys = 5 : 7
The summation of the black keys and white keys = (5 + 7) = 12.
Therefore, if there are 240 keys, the black keys will be
= (5/12) x 240
= (5 x 240)/12
= 100
Therefore, there are 100 black keys.