```
X = [5, 15, 25, 35, 45, 55]
Y = [5, 20, 14, 32, 22, 38]
plt.scatter(X, Y)
```

```
xm=np.mean(X) #valeur moyenne de x
ym=np.mean(Y) #valeur moyenne de y
num=0 #numerator
den=0 #denominator
for i in range(len(X)):
num +=(X[i]-xm)*(Y[i]-ym)
den +=(X[i]-xm)**2
a=num/den
b=ym-a*xm
print(a,b)
```

```
yp=a*X+b #y predict
plt.scatter(X,Y)
plt.plot(X,yp,'r')
```

TypeError: can’t multiply sequence by non-int of type ‘numpy.float64’

i was expecting a predict value

### >Solution :

I believe this is because `X`

is a list and not a numpy array, so you can’t do array operations on it (such as multiplying it by `a`

)

Simple solution could be this:

```
import numpy as np
X = np.array([5, 15, 25, 35, 45, 55])
# rest of your code...
```