settings.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".SettingsActivity" >

  <RadioGroup android:layout_width="fill_parent"
            android:layout_height="wrap_content" android:orientation="vertical"
            android:id="@+id/group1">

            <TextView android:layout_width="fill_parent" android:text="Select Subject :"
                android:layout_height="wrap_content" android:textColor="#ffffff"
                android:textStyle="bold" android:id="@+id/question"/>

            <RadioButton android:checked="false" android:id="@+id/easySetting"  android:text="Easy"/>

            <RadioButton android:checked="false" android:id="@+id/mediumSetting"  android:text="Medium" />

            <RadioButton android:checked="false" android:id="@+id/hardSetting"  android:text="Hard" />

        </RadioGroup>

    <Button android:text="Update" android:id="@+id/nextBtn"
            android:layout_width="80dip" android:layout_alignParentRight="true"
            android:layout_height="wrap_content" android:background="@drawable/button_selector"
            android:paddingTop="5dip" android:paddingBottom="5dip"
            android:textColor="#ffffff" />

</RelativeLayout>