Grammar fixes

Minor grammatic fixes

01 - Data Exploration.ipynb

@@ -6,7 +6,7 @@
    "source": [
     "# Exploring Data with Python\n",
     "\n",
-    "A significant part of a a data scientist's role is to explore, analyze, and visualize data. There's a wide range of tools and programming languages that they can use to do this; and of the most popular approaches is to use Jupyter notebooks (like this one) and Python.\n",
+    "A significant part of a data scientist's role is to explore, analyze, and visualize data. There's a wide range of tools and programming languages that they can use to do this, and of the most popular approaches is to use Jupyter notebooks (like this one) and Python.\n",
     "\n",
     "Python is a flexible programming language that is used in a wide range of scenarios; from web applications to device programming. It's extremely popular in the data science and machine learning community because of the many packages it supports for data analysis and visualization.\n",
     "\n",
@@ -23,7 +23,7 @@
     "\n",
     "## Exploring data arrays with NumPy\n",
     "\n",
-    "Lets start by looking at some simple data.\n",
+    "Let's start by looking at some simple data.\n",
     "\n",
     "Suppose a college takes a sample of student grades for a data science class.\n",
     "\n",
@@ -1558,4 +1558,4 @@
  },
  "nbformat": 4,
  "nbformat_minor": 2
-}
+}